Morte replacements

AABB_tree/include/CGAL/AABB_tree.h

@@ -487,7 +487,7 @@ public:
 			if( size() > 1 ) {
 				delete [] m_p_root_node;
 			}
-			m_p_root_node = NULL;
+			m_p_root_node = nullptr;
     }
 
 		// clears internal KD tree
@@ -495,9 +495,9 @@ public:
 		{
 			if ( m_search_tree_constructed )
 			{
-				CGAL_assertion( m_p_search_tree!=NULL );
+				CGAL_assertion( m_p_search_tree!=nullptr );
 				delete m_p_search_tree;
-				m_p_search_tree = NULL;
+				m_p_search_tree = nullptr;
 				m_search_tree_constructed = false;
                         }
 		}
@@ -607,8 +607,8 @@ public:
   AABB_tree<Tr>::AABB_tree(const Tr& traits)
     : m_traits(traits)
     , m_primitives()
-    , m_p_root_node(NULL)
+    , m_p_root_node(nullptr)
-    , m_p_search_tree(NULL)
+    , m_p_search_tree(nullptr)
     , m_search_tree_constructed(false)
     , m_default_search_tree_constructed(false)
     , m_need_build(false)
@@ -621,8 +621,8 @@ public:
                            T&& ... t)
 		: m_traits()
     , m_primitives()
-		, m_p_root_node(NULL)
+		, m_p_root_node(nullptr)
-		, m_p_search_tree(NULL)
+		, m_p_search_tree(nullptr)
 		, m_search_tree_constructed(false)
     , m_default_search_tree_constructed(false)
     , m_need_build(false)
@@ -687,10 +687,10 @@ public:
 
 			// allocates tree nodes
 			m_p_root_node = new Node[m_primitives.size()-1]();
-			if(m_p_root_node == NULL)
+			if(m_p_root_node == nullptr)
 			{
 				std::cerr << "Unable to allocate memory for AABB tree" << std::endl;
-				CGAL_assertion(m_p_root_node != NULL);
+				CGAL_assertion(m_p_root_node != nullptr);
 				m_primitives.clear();
 				clear();
 			}
@@ -738,7 +738,7 @@ public:
 	{
 		m_p_search_tree = new Search_tree(first, beyond);
                 m_default_search_tree_constructed = true;
-		if(m_p_search_tree != NULL)
+		if(m_p_search_tree != nullptr)
 		{
 			m_search_tree_constructed = true;
 			return true;

AABB_tree/include/CGAL/internal/AABB_tree/AABB_node.h

@@ -47,8 +47,8 @@ public:
   /// Constructor
   AABB_node()
     : m_bbox()
-    , m_p_left_child(NULL)
+    , m_p_left_child(nullptr)
-    , m_p_right_child(NULL)      { };
+    , m_p_right_child(nullptr)      { };
 
   /// Non virtual Destructor
   /// Do not delete children because the tree hosts and delete them

AABB_tree/include/CGAL/internal/AABB_tree/AABB_search_tree.h

@@ -107,7 +107,7 @@ namespace CGAL
         public:
                 template <class ConstPointIterator>
                 AABB_search_tree(ConstPointIterator begin, ConstPointIterator beyond)
-                    : m_p_tree(NULL)
+                    : m_p_tree(nullptr)
                 {
                         typedef typename Add_decorated_point<Traits, typename Traits::Primitive::Id>::Point_3 Decorated_point;
                         std::vector<Decorated_point> points;
@@ -117,7 +117,7 @@ namespace CGAL
                                 ++begin;
                         }
                         m_p_tree = new Tree(points.begin(), points.end());
-                        if(m_p_tree != NULL)
+                        if(m_p_tree != nullptr)
                                 m_p_tree->build();
                         else
                                 std::cerr << "unable to build the search tree!" << std::endl;

AABB_tree/include/CGAL/internal/AABB_tree/Has_nested_type_Shared_data.h

@@ -66,13 +66,13 @@ struct Cstr_shared_data<Graph, Base, ObjectPropertyMap, PointPropertyMap, ::CGAL
   typedef void* Shared_data;
   static Shared_data construct_shared_data(Graph&)
   {
-    return NULL;
+    return nullptr;
   }
 
   template <class VertexPmap>
   static Shared_data construct_shared_data(Graph&, VertexPmap)
   {
-    return NULL;
+    return nullptr;
   }
 };
 

Advancing_front_surface_reconstruction/include/CGAL/Advancing_front_surface_reconstruction.h

@@ -88,7 +88,7 @@ namespace CGAL {
     }
 
     Advancing_front_surface_reconstruction_boundary_iterator(const Surface& S_)
-      : S(S_), pos(NULL)
+      : S(S_), pos(nullptr)
     {}
 
     Advancing_front_surface_reconstruction_boundary_iterator(const Self& s)
@@ -108,7 +108,7 @@ namespace CGAL {
 
     Self operator++()
     {
-      if(pos == NULL) {
+      if(pos == nullptr) {
         return *this;
       }
       if(first){
@@ -134,7 +134,7 @@ namespace CGAL {
 
     void advance_on_boundary()
     {
-      if(pos == NULL) {
+      if(pos == nullptr) {
         return;
       }
       pos = pos->first_incident()->first;
@@ -143,7 +143,7 @@ namespace CGAL {
 
     void advance_to_next_boundary()
     {
-      if(pos == NULL) {
+      if(pos == nullptr) {
         return;
       }
       do {
@@ -157,7 +157,7 @@ namespace CGAL {
         CGAL_assertion(pos->is_on_border());
 
       } else {
-        pos = NULL;
+        pos = nullptr;
       }
     }
   };
@@ -400,18 +400,18 @@ namespace CGAL {
 
       Intern_successors_type* ret = &ist_pool.back();
 
-      ret->first->first = NULL;
+      ret->first->first = nullptr;
-      ret->second->first = NULL;
+      ret->second->first = nullptr;
       return ret;
     }
 
 
     inline bool is_on_border(Vertex_handle vh, const int& i) const
     {
-      if (vh->m_incident_border == NULL) return false; //vh is interior
+      if (vh->m_incident_border == nullptr) return false; //vh is interior
-      if (vh->m_incident_border->first->first != NULL)
+      if (vh->m_incident_border->first->first != nullptr)
 	{
-	  if (vh->m_incident_border->second->first != NULL)
+	  if (vh->m_incident_border->second->first != nullptr)
 	    return ((vh->m_incident_border->first->second.second == i)||
 		    (vh->m_incident_border->second->second.second == i));
 	  return (vh->m_incident_border->first->second.second == i);
@@ -422,28 +422,28 @@ namespace CGAL {
 
     void remove_border_edge(Vertex_handle w, Vertex_handle v)
     {
-      if (w->m_incident_border != NULL)
+      if (w->m_incident_border != nullptr)
 	{
 	  if (w->m_incident_border->second->first == v)
 	    {
-	      w->m_incident_border->second->first = NULL;
+	      w->m_incident_border->second->first = nullptr;
 	      set_interior_edge(w,v);
 	      return;
 	    }
 	  if (w->m_incident_border->first->first == v)
 	    {
-	      if (w->m_incident_border->second->first != NULL)
+	      if (w->m_incident_border->second->first != nullptr)
 		{
 		  Next_border_elt* tmp = w->m_incident_border->first;
 		  w->m_incident_border->first = w->m_incident_border->second;
 		  w->m_incident_border->second = tmp;
-		  w->m_incident_border->second->first = NULL;
+		  w->m_incident_border->second->first = nullptr;
 		  set_interior_edge(w,v);
 		  return;
 		}
 	      else
 		{
-		  w->m_incident_border->first->first = NULL;
+		  w->m_incident_border->first->first = nullptr;
 		  set_interior_edge(w,v);
 		  return;
 		}
@@ -571,7 +571,7 @@ namespace CGAL {
 
     void re_init(Vertex_handle w)
     {
-      if (w->m_incident_border != NULL)
+      if (w->m_incident_border != nullptr)
 	{
 	  w->delete_border();
 	}
@@ -629,7 +629,7 @@ namespace CGAL {
 
     void clear_vertex(Vertex_handle w)
     {
-      if (w->m_incident_border != NULL)
+      if (w->m_incident_border != nullptr)
 	{
 	  w->delete_border();
 	}
@@ -956,14 +956,14 @@ namespace CGAL {
     bool is_border_elt(Edge_like& key, Border_elt& result) const
     {
       Next_border_elt* it12 = border_elt(key.first, key.second);
-      if (it12 != NULL)
+      if (it12 != nullptr)
         {
           result = it12->second;
           return true;
         }
 
       Next_border_elt* it21 =  border_elt(key.second, key.first);
-      if (it21 != NULL)
+      if (it21 != nullptr)
         {
           result = it21->second;
           std::swap(key.first, key.second);
@@ -975,13 +975,13 @@ namespace CGAL {
     //---------------------------------------------------------------------
     bool is_border_elt(Edge_like& key) const {
       Next_border_elt* it12 =  border_elt(key.first, key.second);
-      if (it12 != NULL)
+      if (it12 != nullptr)
         {
           return true;
         }
 
       Next_border_elt* it21 =  border_elt(key.second, key.first);
-      if (it21 != NULL)
+      if (it21 != nullptr)
         {
           std::swap(key.first, key.second);
           return true;
@@ -993,7 +993,7 @@ namespace CGAL {
     bool is_ordered_border_elt(const Edge_like& key, Border_elt& result) const
     {
       Next_border_elt* it12 =  border_elt(key.first, key.second);
-      if (it12 != NULL)
+      if (it12 != nullptr)
         {
           result = it12->second;
           return true;
@@ -1015,7 +1015,7 @@ namespace CGAL {
       Vertex_handle v1 = e.first;
 
       Next_border_elt* it12 =  border_elt(v1, e.second);
-      if (it12 != NULL)
+      if (it12 != nullptr)
         {
           ptr = &it12->second.first.second;
           return true;
@@ -1047,7 +1047,7 @@ namespace CGAL {
 
     coord_type lazy_squared_radius(const Cell_handle& c)
     {
-      if (c->lazy_squared_radius() != NULL)
+      if (c->lazy_squared_radius() != nullptr)
         return *(c->lazy_squared_radius());
 
       c->set_lazy_squared_radius
@@ -1060,7 +1060,7 @@ namespace CGAL {
 
     Point lazy_circumcenter(const Cell_handle& c)
     {
-      if (c->lazy_circumcenter() != NULL)
+      if (c->lazy_circumcenter() != nullptr)
         return *(c->lazy_circumcenter());
 
       c->set_lazy_circumcenter

Advancing_front_surface_reconstruction/include/CGAL/Advancing_front_surface_reconstruction_cell_base_3.h

@@ -75,9 +75,9 @@ namespace CGAL {
 
     Advancing_front_surface_reconstruction_cell_base_3()
       : Cb(),
-        _smallest_radius_facet_tab(NULL), selected_facet(0)
+        _smallest_radius_facet_tab(nullptr), selected_facet(0)
 #ifdef AFSR_LAZY
-      , _circumcenter(NULL), _squared_radius(NULL)
+      , _circumcenter(nullptr), _squared_radius(nullptr)
 #endif
     {
 #ifdef AFSR_FACET_NUMBER
@@ -89,9 +89,9 @@ namespace CGAL {
 
     Advancing_front_surface_reconstruction_cell_base_3(Vertex_handle v0, Vertex_handle v1, Vertex_handle v2, Vertex_handle v3)
       : Cb( v0, v1, v2, v3),
-        _smallest_radius_facet_tab(NULL), selected_facet(0)
+        _smallest_radius_facet_tab(nullptr), selected_facet(0)
 #ifdef AFSR_LAZY
-      , _circumcenter(NULL), _squared_radius(NULL)
+      , _circumcenter(nullptr), _squared_radius(nullptr)
 #endif
     {
 #ifdef FACET_NUMBER
@@ -105,9 +105,9 @@ namespace CGAL {
                                                        Cell_handle n0, Cell_handle n1, Cell_handle n2, Cell_handle n3)
       : Cb(v0,  v1,  v2, v3,
            n0,  n1,  n2, n3),
-        _smallest_radius_facet_tab(NULL), selected_facet(0)
+        _smallest_radius_facet_tab(nullptr), selected_facet(0)
 #ifdef AFSR_LAZY
-      , _circumcenter(NULL), _squared_radius(NULL)
+      , _circumcenter(nullptr), _squared_radius(nullptr)
 #endif
     {
 #ifdef AFSR_FACET_NUMBER
@@ -121,12 +121,12 @@ namespace CGAL {
 
     inline ~Advancing_front_surface_reconstruction_cell_base_3()
     {
-      if (_smallest_radius_facet_tab != NULL)
+      if (_smallest_radius_facet_tab != nullptr)
         delete[] _smallest_radius_facet_tab;
 #ifdef AFSR_LAZY
-      if (_circumcenter != NULL)
+      if (_circumcenter != nullptr)
 	delete _circumcenter;
-      if (_squared_radius != NULL)
+      if (_squared_radius != nullptr)
 	delete _squared_radius;
 #endif
     }
@@ -136,31 +136,31 @@ namespace CGAL {
 
     inline void clear()
     {
-      if (_smallest_radius_facet_tab != NULL)
+      if (_smallest_radius_facet_tab != nullptr)
 	delete[] _smallest_radius_facet_tab;
-      _smallest_radius_facet_tab = NULL;
+      _smallest_radius_facet_tab = nullptr;
       selected_facet = 0;
 #ifdef AFSR_LAZY
-      if (_circumcenter != NULL)
+      if (_circumcenter != nullptr)
 	delete _circumcenter;
-      _circumcenter = NULL;
+      _circumcenter = nullptr;
-      if (_squared_radius != NULL)
+      if (_squared_radius != nullptr)
 	delete _squared_radius;
-      _squared_radius = NULL;
+      _squared_radius = nullptr;
 #endif
     }
 
     //-------------------------------------------------------------------
     inline coord_type smallest_radius(const int& i)
     {
-      if (_smallest_radius_facet_tab == NULL)
+      if (_smallest_radius_facet_tab == nullptr)
 	return -1;
       return _smallest_radius_facet_tab[i];
     }
 
     inline void set_smallest_radius(const int& i, const coord_type& c)
     {
-      if (_smallest_radius_facet_tab == NULL)
+      if (_smallest_radius_facet_tab == nullptr)
 	{
 	  _smallest_radius_facet_tab = new coord_type[4];
 	  for(int i = 0; i < 4; i++)
@@ -172,7 +172,7 @@ namespace CGAL {
     // pour un controle de l'allocation memoire... utile???
     inline bool alloc_smallest_radius_tab(coord_type* ptr)
     {
-      if (_smallest_radius_facet_tab==NULL)
+      if (_smallest_radius_facet_tab==nullptr)
 	{
 	  _smallest_radius_facet_tab = ptr;
 	  return true;

Advancing_front_surface_reconstruction/include/CGAL/Advancing_front_surface_reconstruction_vertex_base_3.h

@@ -174,20 +174,20 @@ namespace CGAL {
 
     void delete_border()
     {
-      m_incident_border = NULL;
+      m_incident_border = nullptr;
     }
 
 
     inline Next_border_elt* next_on_border(const int& i) const
     {
-      if (m_incident_border == NULL) return NULL; //vh is interior
+      if (m_incident_border == nullptr) return nullptr; //vh is interior
-      if (m_incident_border->first->first != NULL)
+      if (m_incident_border->first->first != nullptr)
 	if (m_incident_border->first->second.second == i)
 	  return m_incident_border->first;
-      if (m_incident_border->second->first != NULL)
+      if (m_incident_border->second->first != nullptr)
 	if (m_incident_border->second->second.second == i)
 	  return m_incident_border->second;
-      return NULL;
+      return nullptr;
     }
 
 
@@ -195,40 +195,40 @@ namespace CGAL {
 
     inline bool is_border_edge(Vertex_handle v) const
     {
-      if (m_incident_border == NULL) return false;
+      if (m_incident_border == nullptr) return false;
       return ((m_incident_border->first->first == v)||
 	      (m_incident_border->second->first == v));
     }
 
     inline Next_border_elt* border_elt(Vertex_handle v) const
     {
-      if (m_incident_border == NULL) return NULL;
+      if (m_incident_border == nullptr) return nullptr;
       if (m_incident_border->first->first == v) return m_incident_border->first;
       if (m_incident_border->second->first == v) return m_incident_border->second;
-      return NULL;
+      return nullptr;
     }
 
   public:
     inline Next_border_elt* first_incident() const
     {
-      if (m_incident_border == NULL) return NULL;
+      if (m_incident_border == nullptr) return nullptr;
       return m_incident_border->first;
     }
   private:
     inline Next_border_elt* second_incident() const
     {
-      if (m_incident_border == NULL) return NULL;
+      if (m_incident_border == nullptr) return nullptr;
       return m_incident_border->second;
     }
 
 
     inline  void set_next_border_elt(const Next_border_elt& elt)
     {
-      if (m_incident_border->first->first == NULL)
+      if (m_incident_border->first->first == nullptr)
 	*m_incident_border->first = elt;
       else
 	{
-	  if (m_incident_border->second->first != NULL)
+	  if (m_incident_border->second->first != nullptr)
 	    std::cerr << "+++probleme de MAJ du bord <Vertex_base>" << std::endl;
 	  *m_incident_border->second = elt;
 	}

Algebraic_foundations/include/CGAL/Test/_test_algebraic_structure.h

@@ -417,7 +417,7 @@ void test_algebraic_structure_intern(
     assert( a !=  AS (0));
     assert( b !=  AS (0));
     assert( c !=  AS (0));
-    //  AS (0) == NULL of IntegralDomain
+    //  AS (0) == nullptr of IntegralDomain
     assert(a* AS (0)== AS (0));
     assert(a+ AS (0)==a);
     assert(b* AS (0)== AS (0));

Alpha_shapes_2/include/CGAL/Alpha_shape_2.h

@@ -1333,7 +1333,7 @@ Alpha_shape_2<Dt,EACT>::number_of_solid_components(const Type_of_alpha& alpha) c
        ++face_it) 
     {
       Face_handle pFace = face_it;
-      CGAL_triangulation_postcondition( pFace != NULL);
+      CGAL_triangulation_postcondition( pFace != nullptr);
       
       if (classify(pFace, alpha) == INTERIOR){
 	Data& data = marked_face_set[pFace];
@@ -1367,7 +1367,7 @@ Alpha_shape_2<Dt,EACT>::traverse(const Face_handle& pFace,
     for (int i=0; i<3; i++)
       {
 	pNeighbor = fh->neighbor(i);
-	 CGAL_triangulation_assertion(pNeighbor != NULL);
+	 CGAL_triangulation_assertion(pNeighbor != nullptr);
 	if (classify(pNeighbor, alpha) == INTERIOR){
 	  Data& data = marked_face_set[pNeighbor];
 	  if(data == false){

Alpha_shapes_2/include/CGAL/internal/Lazy_alpha_nt_2.h

@@ -260,26 +260,26 @@ public:
     : exact_(Exact_nt(0)), approx_(0)
   {
     data().nbpts=0;
-    data().p0=NULL;
+    data().p0=nullptr;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
   }
 
   Lazy_alpha_nt_2(double d)
    : exact_(Exact_nt(d)), approx_(d)
   {
     data().nbpts=0;
-    data().p0=NULL;
+    data().p0=nullptr;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
   }
 
   Lazy_alpha_nt_2(const Input_point& wp0)
   {
     data().nbpts=1;
     data().p0=&wp0;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
     set_approx();
   }
 
@@ -289,7 +289,7 @@ public:
     data().nbpts=2;
     data().p0=&wp0;
     data().p1=&wp1;
-    data().p2=NULL;
+    data().p2=nullptr;
     set_approx();
   }
 

Alpha_shapes_3/include/CGAL/Alpha_shape_3.h

@@ -1731,7 +1731,7 @@ Alpha_shape_3<Dt,EACT>::number_of_solid_components(const NT& alpha) const
   for( cell_it = finite_cells_begin(); cell_it != done; ++cell_it)
     {
       Cell_handle pCell = cell_it;
-      CGAL_triangulation_assertion(pCell != NULL);
+      CGAL_triangulation_assertion(pCell != nullptr);
       
       if (classify(pCell, alpha) == INTERIOR){
 	Data& data = marked_cell_set[pCell];
@@ -1763,7 +1763,7 @@ void Alpha_shape_3<Dt,EACT>::traverse(Cell_handle pCell,
     for (int i=0; i<=3; i++)
       {
 	pNeighbor = pCell->neighbor(i);
-	CGAL_triangulation_assertion(pNeighbor != NULL);
+	CGAL_triangulation_assertion(pNeighbor != nullptr);
 	if (classify(pNeighbor, alpha) == INTERIOR){
 	  Data& data = marked_cell_set[pNeighbor];
 	  if(data == false){

Alpha_shapes_3/include/CGAL/internal/Lazy_alpha_nt_3.h

@@ -253,29 +253,29 @@ public:
    : exact_(Exact_nt(0)),approx_(0)
   {
     data().nbpts=0;
-    data().p0=NULL;
+    data().p0=nullptr;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
-    data().p3=NULL;
+    data().p3=nullptr;
   }
   
   Lazy_alpha_nt_3(double d)
    : exact_(Exact_nt(d)),approx_(d)
   {
     data().nbpts=0;
-    data().p0=NULL;
+    data().p0=nullptr;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
-    data().p3=NULL;
+    data().p3=nullptr;
   }
   
   Lazy_alpha_nt_3(const Input_point& wp1)
   {
     data().nbpts=1;
     data().p0=&wp1;
-    data().p1=NULL;
+    data().p1=nullptr;
-    data().p2=NULL;
+    data().p2=nullptr;
-    data().p3=NULL;
+    data().p3=nullptr;
     set_approx();
   }
 
@@ -285,8 +285,8 @@ public:
     data().nbpts=2;
     data().p0=&wp1;
     data().p1=&wp2;
-    data().p2=NULL;
+    data().p2=nullptr;
-    data().p3=NULL;
+    data().p3=nullptr;
     set_approx();
   }
 
@@ -298,7 +298,7 @@ public:
     data().p0=&wp1;
     data().p1=&wp2;
     data().p2=&wp3;
-    data().p3=NULL;
+    data().p3=nullptr;
     set_approx();
   }
 

Apollonius_graph_2/doc/Apollonius_graph_2/Concepts/ApolloniusGraphHierarchyVertexBase_2.h

@@ -63,7 +63,7 @@ ApolloniusGraphHierarchyVertexBase_2(Site_2 s, Face_handle f).;
 /*!
 Returns a handle to the corresponding 
 vertex of the next level Apollonius graph. If such a vertex does not 
-exist `Vertex_handle(NULL)` is returned. 
+exist `Vertex_handle(nullptr)` is returned. 
 */ 
 Vertex_handle up(); 
 

Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrangementDcelFace.h

@@ -72,7 +72,7 @@ bool is_unbounded() const;
 
 /*!
 returns an incident halfedge along the outer boundary of the face. 
-If `f` has no outer boundary, the function returns `NULL`. 
+If `f` has no outer boundary, the function returns `nullptr`. 
 */ 
 Halfedge* halfedge(); 
 

Arrangement_on_surface_2/doc/Arrangement_on_surface_2/Concepts/ArrangementInputFormatter.h

@@ -102,7 +102,7 @@ void read_arrangement_end ();
 /*!
 reads a size value, which is supposed to be preceded by the given label. 
 */ 
-Size read_size (const char *label = NULL); 
+Size read_size (const char *label = nullptr); 
 
 /*!
 reads a message indicating the beginning of the vertex records. 

Arrangement_on_surface_2/include/CGAL/Arr_Bezier_curve_traits_2.h

@@ -167,8 +167,8 @@ public:
       delete p_cache;
       delete p_inter_map;
     }
-    p_cache = NULL;
+    p_cache = nullptr;
-    p_inter_map = NULL;
+    p_inter_map = nullptr;
   }
   //@}
 

Arrangement_on_surface_2/include/CGAL/Arr_accessor.h

@@ -167,7 +167,7 @@ public:
 
     DHalfedge* he = p_arr->_locate_around_vertex(p_arr->_vertex (vh), cv, ind);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for (he));
   }
 
@@ -198,7 +198,7 @@ public:
     DHalfedge* he = p_arr->topology_traits()->
       locate_around_boundary_vertex(p_arr->_vertex (vh), cv, ind, ps_x, ps_y);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for (he));
   }
 
@@ -219,10 +219,10 @@ public:
     
     if (he1 == he2) return (0);
 
-    const DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : NULL;
+    const DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : nullptr;
-    const DOuter_ccb* oc1 = (ic1 == NULL) ? he1->outer_ccb() : NULL;
+    const DOuter_ccb* oc1 = (ic1 == nullptr) ? he1->outer_ccb() : nullptr;
-    const DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : NULL;
+    const DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : nullptr;
-    const DOuter_ccb* oc2 = (ic2 == NULL) ? he2->outer_ccb() : NULL;
+    const DOuter_ccb* oc2 = (ic2 == nullptr) ? he2->outer_ccb() : nullptr;
 
     if ((oc1 != oc2) || (ic1 != ic2)) return (-1);
 
@@ -305,7 +305,7 @@ public:
   Vertex_handle create_vertex(const Point_2& p)
   {
     DVertex* v = p_arr->_create_vertex (p);
-    CGAL_assertion(v != NULL);
+    CGAL_assertion(v != nullptr);
     return (p_arr->_handle_for (v));
   }
   
@@ -328,7 +328,7 @@ public:
   {
     DVertex* v = p_arr->_create_boundary_vertex (cv, ind, ps_x, ps_y);
 
-    CGAL_assertion(v != NULL);
+    CGAL_assertion(v != nullptr);
 
     // Notify the topology traits on the creation of the boundary vertex.
     if (notify)
@@ -359,7 +359,7 @@ public:
     DVertex* v = p_arr->_place_and_set_curve_end(p_arr->_face (f), cv, ind,
                                                  ps_x, ps_y, &pred);
 
-    if (pred == NULL)
+    if (pred == nullptr)
       // No predecessor halfedge, return just the vertex:
       return (std::make_pair(p_arr->_handle_for(v), Halfedge_handle()));
 
@@ -401,7 +401,7 @@ public:
                                                new_face, swapped_predecessors,
                                                allow_swap_of_predecessors);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for(he));
   }
 
@@ -438,7 +438,7 @@ public:
     DHalfedge* he =
       p_arr->_insert_from_vertex(p_arr->_halfedge(he_to), cv, cv_dir, p_v);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for (he));
   }
 
@@ -485,7 +485,7 @@ public:
     DHalfedge* he = p_arr->_insert_in_face_interior(p_arr->_face (f),
                                                     cv, cv_dir, p_v1, p_v2);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for (he));
   
   }
@@ -613,7 +613,7 @@ public:
   {
     DHalfedge* he = p_arr->_split_edge (p_arr->_halfedge(e), p, cv1, cv2);
 
-    CGAL_assertion(he != NULL);
+    CGAL_assertion(he != nullptr);
     return (p_arr->_handle_for(he));
   }
 
@@ -636,7 +636,7 @@ public:
     DHalfedge* he = p_arr->_split_edge(p_arr->_halfedge(e), p_arr->_vertex(v),
                                        cv1, cv2);
 
-    CGAL_assertion (he != NULL);
+    CGAL_assertion (he != nullptr);
     return (p_arr->_handle_for(he));
   }
 
@@ -673,7 +673,7 @@ public:
   {
     DFace* f =
       p_arr->_remove_edge(p_arr->_halfedge (e), remove_source, remove_target);
-    CGAL_assertion(f != NULL);
+    CGAL_assertion(f != nullptr);
     return (p_arr->_handle_for(f));
   }
 
@@ -687,9 +687,9 @@ public:
   {
      DHalfedge* he1 = p_arr->_halfedge(e1);
      DHalfedge* he2 = p_arr->_halfedge(e2);
-    const DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : NULL;
+    const DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : nullptr;
-    if (ic1 == NULL) return (false);
+    if (ic1 == nullptr) return (false);
-    const DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : NULL;
+    const DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : nullptr;
     return (ic1 == ic2);
   }
 
@@ -703,9 +703,9 @@ public:
   {
      DHalfedge* he1 = p_arr->_halfedge(e1);
      DHalfedge* he2 = p_arr->_halfedge(e2);
-    const DOuter_ccb* oc1 = (he1->is_on_outer_ccb()) ? he1->outer_ccb() : NULL;
+    const DOuter_ccb* oc1 = (he1->is_on_outer_ccb()) ? he1->outer_ccb() : nullptr;
-    if (oc1 == NULL) return (false);
+    if (oc1 == nullptr) return (false);
-    const DOuter_ccb* oc2 = (he2->is_on_outer_ccb()) ? he2->outer_ccb() : NULL;
+    const DOuter_ccb* oc2 = (he2->is_on_outer_ccb()) ? he2->outer_ccb() : nullptr;
     return (oc1 == oc2);
   }
   //@}
@@ -797,7 +797,7 @@ public:
 
   /*!
    * Create a new vertex.
-   * \param p A pointer to the point (may be NULL in case of a vertex at
+   * \param p A pointer to the point (may be nullptr in case of a vertex at
    *          infinity).
    * \param ps_x The boundary condition at x.
    * \param ps_y The boundary condition at y.
@@ -807,14 +807,14 @@ public:
                           Arr_parameter_space ps_x, Arr_parameter_space ps_y)
   {
     Dcel_vertex* new_v = p_arr->_dcel().new_vertex();
-    if (p != NULL) {
+    if (p != nullptr) {
       typename Dcel::Vertex::Point* p_pt = p_arr->_new_point(*p);
       new_v->set_point(p_pt);
     }
     else
     {
       CGAL_precondition (p_arr->is_open(ps_x, ps_y));
-      new_v->set_point (NULL);
+      new_v->set_point (nullptr);
     }
 
     new_v->set_boundary (ps_x, ps_y);
@@ -823,7 +823,7 @@ public:
 
   /*!
    * Create a new edge (halfedge pair), associated with the given curve.
-   * \param cv A pointer to the x-monotone curve (may be NULL in case of
+   * \param cv A pointer to the x-monotone curve (may be nullptr in case of
    *           a fictitious edge).
    * \return A pointer to one of the created DCEL halfedge.
    */
@@ -831,11 +831,11 @@ public:
   {
     Dcel_halfedge* new_he = p_arr->_dcel().new_edge();
 
-    if (cv != NULL) {
+    if (cv != nullptr) {
       typename Dcel::Halfedge::X_monotone_curve* p_cv = p_arr->_new_curve(*cv);
       new_he->set_curve(p_cv);
     }
-    else new_he->set_curve(NULL);
+    else new_he->set_curve(nullptr);
     return new_he;
   }
 

Arrangement_on_surface_2/include/CGAL/Arr_bounded_planar_topology_traits_2.h

@@ -132,13 +132,13 @@ public:
   /*! Default constructor. */
   Arr_bounded_planar_topology_traits_2() :
     Base(),
-    unb_face(NULL)
+    unb_face(nullptr)
   {}
 
   /*! Constructor from a geometry-traits object. */
   Arr_bounded_planar_topology_traits_2(const Gt2* traits) :
     Base(traits),
-    unb_face(NULL)
+    unb_face(nullptr)
   {}
 
   /*! Assign the contents of another topology-traits class. */
@@ -347,7 +347,7 @@ public:
                                 Arr_parameter_space /* ps_y */) const
   {
     CGAL_error();
-    return NULL;
+    return nullptr;
   }
 
   /*! Locate a DCEL feature that contains the given curve end.
@@ -379,7 +379,7 @@ public:
   {
     // This function should never be called:
     CGAL_error();
-    return NULL;
+    return nullptr;
   }
 
   /*! Determine whether the given face is unbounded.
@@ -406,7 +406,7 @@ public:
   {
     // This function should never be called:
     CGAL_error();
-    return NULL;
+    return nullptr;
   }
 
     //! reference_face (const version).

Arrangement_on_surface_2/include/CGAL/Arr_curve_data_traits_2.h

@@ -137,13 +137,13 @@ public:
              base_objects.begin(); it != base_objects.end(); ++it)
       {
         base_x_curve = object_cast<Base_x_monotone_curve_2>(&(*it));
-        if (base_x_curve != NULL) {
+        if (base_x_curve != nullptr) {
           // Current object is an x-monotone curve: Attach data to it.
           *oi++ = make_object(X_monotone_curve_2(*base_x_curve, xdata));
         }
         else {
           // Current object is an isolated point: Leave it as is.
-          CGAL_assertion(object_cast<Point_2>(&(*it)) != NULL);
+          CGAL_assertion(object_cast<Point_2>(&(*it)) != nullptr);
           *oi++ = *it;
         }
       }
@@ -219,7 +219,7 @@ public:
       for (typename std::list<CGAL::Object>::const_iterator it =
              base_objects.begin(); it != base_objects.end(); ++it)
       {
-        if ((base_cv = object_cast<Base_x_monotone_curve_2>(&(*it))) != NULL) {
+        if ((base_cv = object_cast<Base_x_monotone_curve_2>(&(*it))) != nullptr) {
           // The current intersection object is an overlapping x-monotone
           // curve: Merge the data fields of both intersecting curves and
           // associate the result with the overlapping curve.

Arrangement_on_surface_2/include/CGAL/Arr_dcel_base.h

@@ -92,31 +92,31 @@ protected:
 public:
   /*! Default constructor. */
   Arr_vertex_base() :
-    p_inc(NULL),
+    p_inc(nullptr),
-    p_pt(NULL)
+    p_pt(nullptr)
   { pss[0] = pss[1] = static_cast<char>(CGAL::ARR_INTERIOR); }
 
   /*! Destructor. */
   virtual ~Arr_vertex_base() {}
 
-  /*! Check if the point pointer is NULL. */
+  /*! Check if the point pointer is nullptr. */
-  bool has_null_point() const { return (p_pt == NULL); }
+  bool has_null_point() const { return (p_pt == nullptr); }
 
   /*! Get the point (const version). */
   const Point& point() const
   {
-    CGAL_assertion(p_pt != NULL);
+    CGAL_assertion(p_pt != nullptr);
     return (*p_pt);
   }
 
   /*! Get the point (non-const version). */
   Point& point()
   {
-    CGAL_assertion(p_pt != NULL);
+    CGAL_assertion(p_pt != nullptr);
     return (*p_pt);
   }
 
-  /*! Set the point (may be a NULL point). */
+  /*! Set the point (may be a nullptr point). */
   void set_point(Point* p) { p_pt = p; }
 
   /*! Get the boundary type in x. */
@@ -175,31 +175,31 @@ protected:
 public:
   /*! Default constructor */
   Arr_halfedge_base() :
-    p_opp(NULL),
+    p_opp(nullptr),
-    p_prev(NULL),
+    p_prev(nullptr),
-    p_next(NULL),
+    p_next(nullptr),
-    p_v(NULL),
+    p_v(nullptr),
-    p_comp(NULL),
+    p_comp(nullptr),
-    p_cv(NULL)
+    p_cv(nullptr)
   {}
 
   /*! Destructor. */
   virtual ~Arr_halfedge_base() {}
 
-  /*! Check if the curve pointer is NULL. */
+  /*! Check if the curve pointer is nullptr. */
-  bool has_null_curve() const { return (p_cv == NULL); }
+  bool has_null_curve() const { return (p_cv == nullptr); }
 
   /*! Get the x-monotone curve (const version). */
   const X_monotone_curve& curve() const
   {
-    CGAL_precondition(p_cv != NULL);
+    CGAL_precondition(p_cv != nullptr);
     return (*p_cv);
   }
 
   /*! Get the x-monotone curve (non-const version). */
   X_monotone_curve& curve()
   {
-    CGAL_precondition(p_cv != NULL);
+    CGAL_precondition(p_cv != nullptr);
     return (*p_cv);
   }
 
@@ -712,7 +712,7 @@ private:
 
 public:
   /*! Default constructor. */
-  Arr_outer_ccb() : p_f(NULL), iter_is_not_singular(false) {}
+  Arr_outer_ccb() : p_f(nullptr), iter_is_not_singular(false) {}
 
   /*! Copy constructor. */
   Arr_outer_ccb(const Arr_outer_ccb& other) :
@@ -778,7 +778,7 @@ private:
 
 public:
   /*! Default constructor. */
-  Arr_inner_ccb() : p_f(NULL), iter_is_not_singular(false) {}
+  Arr_inner_ccb() : p_f(nullptr), iter_is_not_singular(false) {}
 
   /*! Copy constructor. */
   Arr_inner_ccb(const Arr_inner_ccb& other) :
@@ -843,7 +843,7 @@ private:
 
 public:
   /*! Default constructor. */
-  Arr_isolated_vertex() : p_f(NULL), iter_is_not_singular(false) {}
+  Arr_isolated_vertex() : p_f(nullptr), iter_is_not_singular(false) {}
 
   /*! Copy constructor. */
   Arr_isolated_vertex(const Arr_isolated_vertex& other) :

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Bezier_curve_2.h

@@ -117,10 +117,10 @@ public:
   /*! Default constructor. */
   _Bezier_curve_2_rep () :
     _no_self_inter (true),
-    p_polyX(NULL),
+    p_polyX(nullptr),
-    p_normX(NULL),
+    p_normX(nullptr),
-    p_polyY(NULL),
+    p_polyY(nullptr),
-    p_normY(NULL)
+    p_normY(nullptr)
   {}
 
   /*! Copy constructor (isn't really used). */
@@ -128,18 +128,18 @@ public:
     _ctrl_pts(other._ctrl_pts),
     _bbox(other._bbox),
     _no_self_inter(other._no_self_inter),
-    p_polyX(NULL),
+    p_polyX(nullptr),
-    p_normX(NULL),
+    p_normX(nullptr),
-    p_polyY(NULL),
+    p_polyY(nullptr),
-    p_normY(NULL)
+    p_normY(nullptr)
   {
-    if (other.p_polyX != NULL)
+    if (other.p_polyX != nullptr)
       p_polyX = new Polynomial(*(other.p_polyX));
-    if (other.p_polyY != NULL)
+    if (other.p_polyY != nullptr)
       p_polyY = new Polynomial(*(other.p_polyY));
-    if (other.p_normX != NULL)
+    if (other.p_normX != nullptr)
       p_normX = new Integer(*(other.p_normX));
-    if (other.p_normY != NULL)
+    if (other.p_normY != nullptr)
       p_normY = new Integer(*(other.p_normY));
   }
 
@@ -152,10 +152,10 @@ public:
    */
   template <class InputIterator>
   _Bezier_curve_2_rep (InputIterator pts_begin, InputIterator pts_end) :
-    p_polyX(NULL),
+    p_polyX(nullptr),
-    p_normX(NULL),
+    p_normX(nullptr),
-    p_polyY(NULL),
+    p_polyY(nullptr),
-    p_normY(NULL)
+    p_normY(nullptr)
   {
     // Copy the control points and compute their bounding box.
     const int   pts_size = static_cast<int>(std::distance (pts_begin, pts_end));
@@ -218,13 +218,13 @@ public:
   /*! Destructor. */
   ~_Bezier_curve_2_rep ()
   {
-    if (p_polyX != NULL)
+    if (p_polyX != nullptr)
       delete p_polyX;
-    if (p_normX != NULL)
+    if (p_normX != nullptr)
       delete p_normX;
-    if (p_polyY != NULL)
+    if (p_polyY != nullptr)
       delete p_polyY;
-    if (p_normY != NULL)
+    if (p_normY != nullptr)
       delete p_normY;
   }
 
@@ -234,14 +234,14 @@ public:
   /*! Check if the polynomials are already constructed. */
   bool has_polynomials () const
   {
-    return (p_polyX != NULL && p_normX != NULL &&
+    return (p_polyX != nullptr && p_normX != nullptr &&
-            p_polyY != NULL && p_normY != NULL);
+            p_polyY != nullptr && p_normY != nullptr);
   }
 
   /*! Get the polynomial X(t). */
   const Polynomial& x_polynomial () const
   {
-    if (p_polyX == NULL)
+    if (p_polyX == nullptr)
       _construct_polynomials ();
 
     return (*p_polyX);
@@ -250,7 +250,7 @@ public:
   /*! Get the normalizing factor for X(t). */
   const Integer& x_norm () const
   {
-    if (p_normX == NULL)
+    if (p_normX == nullptr)
       _construct_polynomials ();
 
     return (*p_normX);
@@ -259,7 +259,7 @@ public:
   /*! Get the polynomial Y(t). */
   const Polynomial& y_polynomial () const
   {
-    if (p_polyY == NULL)
+    if (p_polyY == nullptr)
       _construct_polynomials ();
 
     return (*p_polyY);
@@ -268,7 +268,7 @@ public:
   /*! Get the normalizing factor for Y(t). */
   const Integer& y_norm () const
   {
-    if (p_normY == NULL)
+    if (p_normY == nullptr)
       _construct_polynomials ();
 
     return (*p_normY);

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Bezier_point_2.h

@@ -108,7 +108,7 @@ private:
     Originator (const Curve_2& c, const Algebraic& t) :
       _curve (c),
       _xid (0),
-      p_t (NULL)
+      p_t (nullptr)
     {
       set_parameter (t);
     }
@@ -118,7 +118,7 @@ private:
                 const Algebraic& t) :
       _curve (c),
       _xid (xid),
-      p_t (NULL)
+      p_t (nullptr)
     {
       set_parameter (t);
     }
@@ -128,7 +128,7 @@ private:
       _curve (c),
       _xid (0),
       _bpb (bpb),
-      p_t (NULL)
+      p_t (nullptr)
     {}
 
     /*! Constructor with bounding information and no exact representation. */
@@ -137,7 +137,7 @@ private:
       _curve (c),
       _xid (xid),
       _bpb (bpb),
-      p_t (NULL)
+      p_t (nullptr)
     {}
 
     /*! Copy constructor. */
@@ -145,17 +145,17 @@ private:
       _curve (other._curve),
       _xid (other._xid),
       _bpb (other._bpb),
-      p_t (NULL)
+      p_t (nullptr)
     {
       // Deep copy of lazy instantiation
-      if (other.p_t != NULL)
+      if (other.p_t != nullptr)
         p_t = new Algebraic (*(other.p_t));
     }
 
     /*! Destructor. */
     ~Originator() 
     {
-      if (p_t != NULL)
+      if (p_t != nullptr)
         delete p_t;
     }
 
@@ -167,9 +167,9 @@ private:
         return (*this);
 
       // Free memory, if necessary.
-      if (p_t != NULL)
+      if (p_t != nullptr)
         delete p_t;
-      p_t = NULL;
+      p_t = nullptr;
 
       // Copy the data members.
       _curve = other._curve;
@@ -177,7 +177,7 @@ private:
       _bpb = other._bpb;
 
       // Deep copy of lazy instantiation
-      if (other.p_t != NULL)
+      if (other.p_t != nullptr)
         p_t = new Algebraic (*(other.p_t));
 
       return (*this);
@@ -211,7 +211,7 @@ private:
     /*! Check if the algberaic parameter is available. */
     bool has_parameter () const
     {
-      return (p_t != NULL);
+      return (p_t != nullptr);
     }
 
     /*! 
@@ -220,7 +220,7 @@ private:
      */
     const Algebraic& parameter () const
     {
-      CGAL_precondition (p_t != NULL);
+      CGAL_precondition (p_t != nullptr);
       return (*p_t);
     }
 
@@ -230,7 +230,7 @@ private:
      */
     void set_parameter (const Algebraic& t)
     {
-      CGAL_precondition (p_t == NULL);
+      CGAL_precondition (p_t == nullptr);
       
       p_t = new Algebraic (t);
 
@@ -305,28 +305,28 @@ public:
 
   /*! Default constructor. */
   _Bezier_point_2_rep () :
-    p_alg_x (NULL),
+    p_alg_x (nullptr),
-    p_rat_x (NULL),
+    p_rat_x (nullptr),
-    p_alg_y (NULL),
+    p_alg_y (nullptr),
-    p_rat_y (NULL)
+    p_rat_y (nullptr)
   {}
 
   /*! Copy constructor. */
   _Bezier_point_2_rep (const Self& pt) :
-    p_alg_x (NULL),
+    p_alg_x (nullptr),
-    p_rat_x (NULL),
+    p_rat_x (nullptr),
-    p_alg_y (NULL),
+    p_alg_y (nullptr),
-    p_rat_y (NULL),
+    p_rat_y (nullptr),
     _origs (pt._origs),
     _bbox (pt._bbox)
   {
-    if (pt.p_alg_x != NULL)
+    if (pt.p_alg_x != nullptr)
       p_alg_x = new Algebraic (*(pt.p_alg_x));
-    if (pt.p_rat_x != NULL)
+    if (pt.p_rat_x != nullptr)
       p_rat_x = new Rational (*(pt.p_rat_x));
-    if (pt.p_alg_y != NULL)
+    if (pt.p_alg_y != nullptr)
       p_alg_y = new Algebraic (*(pt.p_alg_y));
-    if (pt.p_rat_y != NULL)
+    if (pt.p_rat_y != nullptr)
       p_rat_y = new Rational (*(pt.p_rat_y));
   }
 
@@ -336,8 +336,8 @@ public:
    * \param y The exact y-coordinate.
    */
   _Bezier_point_2_rep (const Algebraic& x, const Algebraic& y, bool) : 
-    p_rat_x (NULL),
+    p_rat_x (nullptr),
-    p_rat_y (NULL)
+    p_rat_y (nullptr)
   {
     p_alg_x = new Algebraic (x);
     p_alg_y = new Algebraic (y);
@@ -407,13 +407,13 @@ public:
   /*! Destructor. */
   ~_Bezier_point_2_rep ()
   {
-    if (p_rat_x != NULL)
+    if (p_rat_x != nullptr)
       delete p_rat_x;
-    if (p_alg_x != NULL)
+    if (p_alg_x != nullptr)
       delete p_alg_x;
-    if (p_rat_y != NULL)
+    if (p_rat_y != nullptr)
       delete p_rat_y;
-    if (p_alg_y != NULL)
+    if (p_alg_y != nullptr)
       delete p_alg_y;
   }
 
@@ -423,24 +423,24 @@ public:
     if (this == &pt)
       return (*this);
 
-    if (p_rat_x != NULL)
+    if (p_rat_x != nullptr)
       delete p_rat_x;
-    if (p_alg_x != NULL)
+    if (p_alg_x != nullptr)
       delete p_alg_x;
-    if (p_rat_y != NULL)
+    if (p_rat_y != nullptr)
       delete p_rat_y;
-    if (p_alg_y != NULL)
+    if (p_alg_y != nullptr)
       delete p_alg_y;
-    p_alg_x = p_rat_x = p_alg_y = p_rat_y = NULL;
+    p_alg_x = p_rat_x = p_alg_y = p_rat_y = nullptr;
 
 
-    if (pt.p_alg_x != NULL)
+    if (pt.p_alg_x != nullptr)
       p_alg_x = new Algebraic (*(pt.p_alg_x));
-    if (pt.p_rat_x != NULL)
+    if (pt.p_rat_x != nullptr)
       p_rat_x = new Rational (*(pt.p_rat_x));
-    if (pt.p_alg_y != NULL)
+    if (pt.p_alg_y != nullptr)
       p_alg_y = new Algebraic (*(pt.p_alg_y));
-    if (pt.p_rat_y != NULL)
+    if (pt.p_rat_y != nullptr)
       p_rat_y = new Rational (*(pt.p_rat_y));
   
     _origs = pt._origs;
@@ -452,13 +452,13 @@ public:
   /*! Check if the point is exactly computed. */
   inline bool is_exact () const
   {
-    return (p_alg_x != NULL && p_alg_y != NULL);
+    return (p_alg_x != nullptr && p_alg_y != nullptr);
   }
 
   /*! Check if the point has rational coordinates. */
   inline bool is_rational () const
   {
-    return (p_rat_x != NULL && p_rat_y != NULL);
+    return (p_rat_x != nullptr && p_rat_y != nullptr);
   }
 
   /*!
@@ -1060,8 +1060,8 @@ _Bezier_point_2_rep<RatKer, AlgKer, NtTrt, BndTrt>::_Bezier_point_2_rep
 template <class RatKer, class AlgKer, class NtTrt, class BndTrt>
 _Bezier_point_2_rep<RatKer, AlgKer, NtTrt, BndTrt>::_Bezier_point_2_rep
         (const Curve_2& B, const Algebraic& t0) :
-  p_rat_x (NULL),
+  p_rat_x (nullptr),
-  p_rat_y (NULL)
+  p_rat_y (nullptr)
 {
   // Create the originator pair <B(t), t0>.
   // Note that this constructor also takes care of the Bez_bound
@@ -1095,8 +1095,8 @@ template <class RatKer, class AlgKer, class NtTrt, class BndTrt>
 _Bezier_point_2_rep<RatKer, AlgKer, NtTrt, BndTrt>::_Bezier_point_2_rep
         (const Curve_2& B, unsigned int xid,
          const Algebraic& t0) :
-  p_rat_x (NULL),
+  p_rat_x (nullptr),
-  p_rat_y (NULL)
+  p_rat_y (nullptr)
 {
   // Create the originator pair <B(t), t0>.
   // Note that this constructor also takes care of the Bez_bound

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Circle_segment_2.h

@@ -1187,7 +1187,7 @@ public:
    */
   template <class OutputIterator>
   OutputIterator intersect (const Self& cv, OutputIterator oi,
-                            Intersection_map *inter_map = NULL) const
+                            Intersection_map *inter_map = nullptr) const
   {
     // First check whether the two arcs have the same supporting curve.
     if (has_same_supporting_curve (cv))
@@ -1232,7 +1232,7 @@ public:
     Intersection_list            inter_list;
     bool                         invalid_ids = false;
 
-    if (inter_map != NULL && _index() != 0 && cv._index() != 0)
+    if (inter_map != nullptr && _index() != 0 && cv._index() != 0)
     {
       if (_index() < cv._index())
         id_pair = Curve_id_pair (_index(), cv._index());
@@ -1245,12 +1245,12 @@ public:
     {
       // In case one of the IDs is invalid, we do not look in the map neither
       // we cache the results.
-      if (inter_map != NULL)
+      if (inter_map != nullptr)
         map_iter = inter_map->end();
       invalid_ids = true;
     }
 
-    if (inter_map == NULL || map_iter == inter_map->end())
+    if (inter_map == nullptr || map_iter == inter_map->end())
     {
       // Compute the intersections points between the two supporting curves.
       if (is_linear())

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Conic_arc_2.h

@@ -114,7 +114,7 @@ protected:
   };
 
   Extra_data    *_extra_data_P;  // The extra data stored with the arc
-                                 // (may be NULL).
+                                 // (may be nullptr).
 
 public:
 
@@ -128,7 +128,7 @@ public:
     _r(0), _s(0), _t(0), _u(0), _v(0), _w(0),
     _orient (COLLINEAR),
     _info (0),
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {}
 
   /*!
@@ -142,10 +142,10 @@ public:
     _source(arc._source),
     _target(arc._target)
   {
-    if (arc._extra_data_P != NULL)
+    if (arc._extra_data_P != nullptr)
       _extra_data_P = new Extra_data (*(arc._extra_data_P));
     else
-      _extra_data_P = NULL;
+      _extra_data_P = nullptr;
   }
 
   /*!
@@ -155,7 +155,7 @@ public:
    */
   _Conic_arc_2 (const Rational& r, const Rational& s, const Rational& t,
                 const Rational& u, const Rational& v, const Rational& w) :
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Make sure the given curve is an ellipse (4rs - t^2 should be positive).
     CGAL_precondition (CGAL::sign (4*r*s - t*t) == POSITIVE);
@@ -189,7 +189,7 @@ public:
     _orient (orient),
     _source (source),
     _target (target),
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Make sure that the source and the taget are not the same.
     CGAL_precondition (Alg_kernel().compare_xy_2_object() (source,
@@ -214,7 +214,7 @@ public:
    */
   _Conic_arc_2 (const Rat_segment_2& seg) :
     _orient (COLLINEAR),
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Set the source and target.
     Rat_kernel        ker;
@@ -271,7 +271,7 @@ public:
    */
   _Conic_arc_2 (const Rat_circle_2& circ) :
     _orient (CLOCKWISE),
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Get the circle properties.
     Rat_kernel        ker;
@@ -316,7 +316,7 @@ public:
     _orient(orient),
     _source(source),
     _target(target),
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Make sure that the source and the taget are not the same.
     CGAL_precondition (Alg_kernel().compare_xy_2_object() (source,
@@ -378,7 +378,7 @@ public:
   _Conic_arc_2 (const Rat_point_2& p1,
                 const Rat_point_2& p2,
                 const Rat_point_2& p3):
-    _extra_data_P (NULL)
+    _extra_data_P (nullptr)
   {
     // Set the source and target.
     Rational          x1 = p1.x();
@@ -467,7 +467,7 @@ public:
 		const Rat_point_2& p3,
 		const Rat_point_2& p4,
 		const Rat_point_2& p5) :
-    _extra_data_P(NULL)
+    _extra_data_P(nullptr)
   {
     // Make sure that no three points are collinear.
     Rat_kernel                         ker;
@@ -574,7 +574,7 @@ public:
 		const Rational& r_2, const Rational& s_2, const Rational& t_2,
 		const Rational& u_2, const Rational& v_2, const Rational& w_2):
     _orient(orient),
-    _extra_data_P(NULL)
+    _extra_data_P(nullptr)
   {
     // Create the integer coefficients of the base conic.
     Rational          rat_coeffs [6];
@@ -753,7 +753,7 @@ public:
    */
   virtual ~_Conic_arc_2 ()
   {
-    if (_extra_data_P != NULL)
+    if (_extra_data_P != nullptr)
       delete _extra_data_P;
   }
 
@@ -767,7 +767,7 @@ public:
       return (*this);
 
     // Free any existing data.
-    if (_extra_data_P != NULL)
+    if (_extra_data_P != nullptr)
       delete _extra_data_P;
 
     // Copy the arc's attributes.
@@ -784,10 +784,10 @@ public:
     _target = arc._target;
 
     // Duplicate the extra data, if necessary.
-    if (arc._extra_data_P != NULL)
+    if (arc._extra_data_P != nullptr)
       _extra_data_P = new Extra_data (*(arc._extra_data_P));
     else
-      _extra_data_P = NULL;
+      _extra_data_P = nullptr;
 
     return (*this);
   }
@@ -1204,7 +1204,7 @@ private:
       return;
     }
 
-    _extra_data_P = NULL;
+    _extra_data_P = nullptr;
 
     // Check whether we have a degree 2 curve.
     if ((CGAL::sign (_r) != ZERO ||
@@ -1339,7 +1339,7 @@ private:
     CGAL_assertion (is_ellipse);
 
     // We do not have to store any extra data with the arc.
-    _extra_data_P = NULL;
+    _extra_data_P = nullptr;
 
     // Mark that this arc is a full conic curve.
     if (is_ellipse)
@@ -1470,9 +1470,9 @@ protected:
   Sign _sign_of_extra_data (const Algebraic& px,
 			    const Algebraic& py) const
   {
-    CGAL_assertion (_extra_data_P != NULL);
+    CGAL_assertion (_extra_data_P != nullptr);
 
-    if (_extra_data_P == NULL)
+    if (_extra_data_P == nullptr)
       return (ZERO);
 
     Algebraic         val = (_extra_data_P->a*px + _extra_data_P->b*py +
@@ -1542,7 +1542,7 @@ protected:
       return (true);
 
     // Check if we have extra data available.
-    if (_extra_data_P != NULL)
+    if (_extra_data_P != nullptr)
     {
       if (_extra_data_P->side != ZERO)
       {

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Conic_x_monotone_arc_2.h

@@ -522,7 +522,7 @@ public:
     }
     else if (this->_orient == COLLINEAR)
     {
-      CGAL_assertion (this->_extra_data_P != NULL);
+      CGAL_assertion (this->_extra_data_P != nullptr);
 
       // In this case the equation of the supporting line is given by the
       // extra data structure.

Arrangement_on_surface_2/include/CGAL/Arr_geometry_traits/Polycurve_2.h

@@ -235,7 +235,7 @@ public:
       m_cvP(cvP),
       m_index(index)
     {
-      m_num_pts = (m_cvP == NULL) ? 0 :
+      m_num_pts = (m_cvP == nullptr) ? 0 :
         ((m_cvP->number_of_subcurves() == 0) ?
          0 : (m_cvP->number_of_subcurves() + 1));
     }
@@ -246,7 +246,7 @@ public:
   public:
     /*! Default constructor. */
     Point_const_iterator() :
-      m_cvP(NULL),
+      m_cvP(nullptr),
       m_num_pts(0),
       m_index(std::numeric_limits<size_type>::max BOOST_PREVENT_MACRO_SUBSTITUTION ())
     {}
@@ -256,7 +256,7 @@ public:
      */
     const Point_type_2& operator*() const
     {
-      CGAL_assertion(m_cvP != NULL);
+      CGAL_assertion(m_cvP != nullptr);
       CGAL_assertion((is_index_valid()) && (m_index < m_num_pts));
 
       // First point is the source of the first subcurve.
@@ -273,28 +273,28 @@ public:
     /*! Increment operators. */
     Point_const_iterator& operator++()
     {
-      if ((m_cvP != NULL) && (m_index < m_num_pts)) ++m_index;
+      if ((m_cvP != nullptr) && (m_index < m_num_pts)) ++m_index;
       return (*this);
     }
 
     Point_const_iterator operator++(int)
     {
       Point_const_iterator temp = *this;
-      if ((m_cvP != NULL) && (m_index < m_num_pts)) ++m_index;
+      if ((m_cvP != nullptr) && (m_index < m_num_pts)) ++m_index;
       return temp;
     }
 
     /*! Decrement operators. */
     Point_const_iterator& operator--()
     {
-      if ((m_cvP != NULL) && (is_index_valid())) --m_index;
+      if ((m_cvP != nullptr) && (is_index_valid())) --m_index;
       return (*this);
     }
 
     Point_const_iterator operator--(int)
     {
       Point_const_iterator temp = *this;
-      if ((m_cvP != NULL) && (is_index_valid())) --m_index;
+      if ((m_cvP != nullptr) && (is_index_valid())) --m_index;
       return temp;
     }
 

Arrangement_on_surface_2/include/CGAL/Arr_landmarks_point_location.h

@@ -114,9 +114,9 @@ protected:
 public:
   /*! Default constructor. */
   Arr_landmarks_point_location() :
-    p_arr(NULL),
+    p_arr(nullptr),
-    m_traits(NULL),
+    m_traits(nullptr),
-    lm_gen(NULL),
+    lm_gen(nullptr),
     own_gen(false)
   {}
 
@@ -141,25 +141,25 @@ public:
   {
     if (own_gen) {
       delete lm_gen;
-      lm_gen = NULL;
+      lm_gen = nullptr;
     }
   }
 
  /*! Attach an arrangement object (and a generator, if supplied). */
-  void attach(const Arrangement_2& arr, Generator* gen = NULL)
+  void attach(const Arrangement_2& arr, Generator* gen = nullptr)
   {
     // Keep a pointer to the associated arrangement.
     p_arr = &arr;
     m_traits = static_cast<const Traits_adaptor_2*>(p_arr->geometry_traits());
 
     // Update the landmarks generator.
-    if (gen != NULL) {
+    if (gen != nullptr) {
       // In case a generator is given, keep a pointer to it.
-      CGAL_assertion(lm_gen == NULL);
+      CGAL_assertion(lm_gen == nullptr);
       lm_gen = gen;
       own_gen = false;
     }
-    else if (lm_gen != NULL) {
+    else if (lm_gen != nullptr) {
       // In case a generator exists internally, make sure it is attached to
       // the given arrangement.
       Arrangement_2& non_const_arr = const_cast<Arrangement_2&>(*p_arr);
@@ -175,10 +175,10 @@ public:
   /*! Detach the instance from the arrangement object. */
   void detach()
   {
-    p_arr = NULL;
+    p_arr = nullptr;
-    m_traits = NULL;
+    m_traits = nullptr;
 
-    CGAL_assertion(lm_gen != NULL);
+    CGAL_assertion(lm_gen != nullptr);
     if (lm_gen)
       lm_gen->detach();
   }

Arrangement_on_surface_2/include/CGAL/Arr_linear_traits_2.h

@@ -1519,7 +1519,7 @@ public:
       // Check whether we have a single intersection point.
       const Point_2  *ip = object_cast<Point_2> (&obj);
 
-      if (ip != NULL)
+      if (ip != nullptr)
       {
         // Check whether the intersection point ip lies on both segments.
         const bool    ip_on_cv1 = cv1.is_vertical() ? cv1.is_in_y_range(*ip) :

Arrangement_on_surface_2/include/CGAL/Arr_naive_point_location.h

@@ -78,9 +78,9 @@ protected:
 public:
   /*! Default constructor. */
   Arr_naive_point_location() : 
-    p_arr(NULL),
+    p_arr(nullptr),
-    geom_traits(NULL),
+    geom_traits(nullptr),
-    top_traits(NULL)
+    top_traits(nullptr)
   {}
         
   /*! Constructor given an arrangement. */
@@ -101,9 +101,9 @@ public:
   /*! Detach from the current arrangement object. */
   void detach()
   {
-    p_arr = NULL;
+    p_arr = nullptr;
-    geom_traits = NULL;
+    geom_traits = nullptr;
-    top_traits = NULL;
+    top_traits = nullptr;
   }
  
   /*!

Arrangement_on_surface_2/include/CGAL/Arr_non_caching_segment_traits_2.h

@@ -241,7 +241,7 @@ public:
       // Chack if the intersection is a point:
       const Point_2             *ip;
 
-      if ((ip = object_cast<Point_2> (&res)) != NULL)
+      if ((ip = object_cast<Point_2> (&res)) != nullptr)
       {
         // Create a pair representing the point with its multiplicity,
         // which is always 1 for line segments for all practical purposes.
@@ -257,7 +257,7 @@ public:
         // The intersection is a segment.
 
         const X_monotone_curve_2 *ov = object_cast<X_monotone_curve_2>(&res);
-        CGAL_assertion (ov != NULL);
+        CGAL_assertion (ov != nullptr);
 
         Self self;
         Comparison_result cmp1 = self.compare_endpoints_xy_2_object()(cv1);

Arrangement_on_surface_2/include/CGAL/Arr_observer.h

@@ -72,7 +72,7 @@ public:
 
   /*! Default constructor. */
   Arr_observer () :
-    p_arr (NULL)
+    p_arr (nullptr)
   {}
 
   /*! Constructor with an associated arrangement. */
@@ -87,7 +87,7 @@ public:
   virtual ~Arr_observer ()
   {
     // Unregister the observer object from the arrangement.
-    if (p_arr != NULL)
+    if (p_arr != nullptr)
       p_arr->_unregister_observer (this);
   }
   //@}
@@ -118,9 +118,9 @@ public:
       return;
 
     // The observer is not already attached to an arrangement.
-    CGAL_precondition (p_arr == NULL);
+    CGAL_precondition (p_arr == nullptr);
 
-    if (p_arr != NULL)
+    if (p_arr != nullptr)
       return;
 
     // Notify the concrete oberver (the sub-class) about the attachment.
@@ -139,7 +139,7 @@ public:
   /*! Detach the observer from the arrangement. */
   void detach ()
   {
-    if (p_arr == NULL)
+    if (p_arr == nullptr)
       return;
 
     // Notify the concrete oberver (the sub-class) about the detachment.
@@ -148,7 +148,7 @@ public:
     // Unregister the observer object from the current arrangement, and mark
     // that the oberver is not attached to an arrangement.
     p_arr->_unregister_observer (this);
-    p_arr = NULL;
+    p_arr = nullptr;
    
     // Notify the concrete oberver that the detachment took place.
     after_detach();

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Arr_landmarks_pl_impl.h

@@ -169,7 +169,7 @@ _walk_from_vertex(Vertex_const_handle nearest_vertex,
       // We found a vertex closer to p; Continue using this vertex.
       const Vertex_const_handle* p_vh =
         Result().template assign<Vertex_const_handle>(obj);
-      CGAL_assertion(p_vh != NULL);
+      CGAL_assertion(p_vh != nullptr);
       vh = *p_vh;
       continue;
     }
@@ -504,7 +504,7 @@ _walk_from_face(Face_const_handle face,
 
   do {
     // Check whether p lies inside the current face (including its holes):
-    if (p_arr->topology_traits()->is_in_face(&(*face), p, NULL))
+    if (p_arr->topology_traits()->is_in_face(&(*face), p, nullptr))
     {
       // We know that p is located inside the current face, and we check
       // whether it lies inside one of its holes (or on the boundary of

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Arr_lm_nearest_neighbor.h

@@ -161,7 +161,7 @@ private:
 public:
   /*! Default constructor. */
   Arr_landmarks_nearest_neighbor () :
-    m_tree(NULL),
+    m_tree(nullptr),
     m_is_empty(true)
   {}
 
@@ -177,7 +177,7 @@ public:
   template <class InputIterator>
   void init(InputIterator begin, InputIterator end)
   {
-    CGAL_precondition_msg(m_tree == NULL,
+    CGAL_precondition_msg(m_tree == nullptr,
                           "The search tree is already initialized.");
 
     if (begin != end) {
@@ -193,9 +193,9 @@ public:
   /*! Clear the search tree. */
   void clear() 
   {
-    if (m_tree != NULL)
+    if (m_tree != nullptr)
       delete m_tree;
-    m_tree = NULL;
+    m_tree = nullptr;
     m_is_empty = true;
   }
 
@@ -209,7 +209,7 @@ public:
    */
   Point_2 find_nearest_neighbor(const Point_2& q, PL_result_type &obj) const
   {
-    CGAL_precondition_msg(m_tree != NULL && ! m_is_empty,
+    CGAL_precondition_msg(m_tree != nullptr && ! m_is_empty,
                           "The search tree is not initialized.");
 
     // Create an NN_Point_2 object from the query point and use it to

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Arr_naive_point_location_impl.h

@@ -79,7 +79,7 @@ Arr_naive_point_location<Arrangement>::locate(const Point_2& p) const
   for (fit = p_arr->faces_begin(); fit != p_arr->faces_end(); ++fit) {
     fh = fit;
   
-    if (top_traits->is_in_face(&(*fh), p, NULL)) {
+    if (top_traits->is_in_face(&(*fh), p, nullptr)) {
       // The current face contains p in its interior.
       if (f_inner == invalid_f ||
           f_inner->is_unbounded() ||
@@ -102,7 +102,7 @@ Arr_naive_point_location<Arrangement>::locate(const Point_2& p) const
           fh->outer_ccbs_begin();
         Vertex_const_handle  v = (*it)->source();
 
-        if (top_traits->is_in_face(&(*f_inner), v->point(), NULL))
+        if (top_traits->is_in_face(&(*f_inner), v->point(), nullptr))
           f_inner = fh;
       }
     }

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Arr_simple_point_location_impl.h

@@ -135,9 +135,9 @@ _base_vertical_ray_shoot(const Point_2& p, bool shoot_up) const
   Comparison_result               res = EQUAL;
   Comparison_result               y_res;
   bool                            in_x_range;
-  const typename Dcel::Halfedge*  closest_he = NULL; // The closest so far.
+  const typename Dcel::Halfedge*  closest_he = nullptr; // The closest so far.
-  const typename Dcel::Vertex*    cl_vs = NULL;      // Its source.
+  const typename Dcel::Vertex*    cl_vs = nullptr;      // Its source.
-  const typename Dcel::Vertex*    cl_vt = NULL;      // Its target.
+  const typename Dcel::Vertex*    cl_vt = nullptr;      // Its target.
 
   while (eit != e_end) {
     // Get the current edge and its source and target vertices.
@@ -158,7 +158,7 @@ _base_vertical_ray_shoot(const Point_2& p, bool shoot_up) const
       res = m_topol_traits->compare_y_at_x(p, he);
 
     if (in_x_range && (res == point_above_under)) {
-      if (closest_he == NULL) {
+      if (closest_he == nullptr) {
         // If no other x-monotone curve containing p in its x-range has been
         // found yet, take the current one as the vertically closest to p.
         closest_he = he;
@@ -242,7 +242,7 @@ _base_vertical_ray_shoot(const Point_2& p, bool shoot_up) const
   }
 
   // If we did not locate a closest halfedge, return an empty object.
-  if (closest_he == NULL)
+  if (closest_he == nullptr)
     return make_optional_result();
 
   // If we found a fictitious edge, return it now.
@@ -305,7 +305,7 @@ Arr_simple_point_location<Arrangement>::_vertical_ray_shoot(const Point_2& p,
     else {
       const Halfedge_const_handle* p_hh =
         Result().template assign<Halfedge_const_handle>(obj);
-      CGAL_assertion(p_hh != NULL);
+      CGAL_assertion(p_hh != nullptr);
       found_halfedge = true;
       closest_he = *p_hh;
     }

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Arr_trapezoid_ric_pl_impl.h

@@ -193,7 +193,7 @@ _get_unbounded_face(const Td_map_item& item,const Point_2& p,
     Td_map_item& left_v_item = td.locate(tr.left(),td_lt);
     CGAL_assertion(td_lt == TD::POINT);
     Halfedge_const_handle he;
-    if (boost::get<Td_active_vertex>(&left_v_item) != NULL) {
+    if (boost::get<Td_active_vertex>(&left_v_item) != nullptr) {
       Td_active_vertex v(boost::get<Td_active_vertex>(left_v_item));
       he = v.cw_he();
     }
@@ -225,7 +225,7 @@ _get_unbounded_face(const Td_map_item& item,const Point_2& p,
     Td_map_item& right_v_item = td.locate(tr.right(),td_lt);
     CGAL_assertion(td_lt == TD::POINT);
     Halfedge_const_handle he;
-    if (boost::get<Td_active_vertex>(&right_v_item)!= NULL) {
+    if (boost::get<Td_active_vertex>(&right_v_item)!= nullptr) {
       Td_active_vertex v(boost::get<Td_active_vertex>(right_v_item));
       he = v.cw_he();
     }

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_X_trapezoid.h

@@ -248,7 +248,7 @@ public:
   
     Curve_end v_ce(left()->curve_end());
     ptr()->e2 = (boost::shared_ptr<X_monotone_curve_2>)(new X_monotone_curve_2(v_ce.cv()));
-    //CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2>>( &(ptr()->e2)) != NULL);
+    //CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2>>( &(ptr()->e2)) != nullptr);
   
     ptr()->e1 = (v_ce.ce() == ARR_MIN_END ) ? CGAL_TD_CV_MIN_END : CGAL_TD_CV_MAX_END;
   
@@ -452,7 +452,7 @@ public:
   CGAL_TD_INLINE Vertex_const_handle left_unsafe() const
     {
     CGAL_precondition(is_active()); 
-    CGAL_assertion(boost::get<Vertex_const_handle>(&(ptr()->e0)) != NULL);
+    CGAL_assertion(boost::get<Vertex_const_handle>(&(ptr()->e0)) != nullptr);
     return boost::get<Vertex_const_handle>(ptr()->e0);
     }
 
@@ -475,7 +475,7 @@ public:
   CGAL_TD_INLINE Vertex_const_handle right_unsafe() const
     {
     CGAL_precondition(is_active()); 
-    CGAL_assertion(boost::get<Vertex_const_handle>(&(ptr()->e1)) != NULL);
+    CGAL_assertion(boost::get<Vertex_const_handle>(&(ptr()->e1)) != nullptr);
     return boost::get<Vertex_const_handle>(ptr()->e1);
     }
 
@@ -498,7 +498,7 @@ public:
   CGAL_TD_INLINE Halfedge_const_handle bottom_unsafe () const
   {
     CGAL_precondition(is_active()); 
-    CGAL_assertion(boost::get<Halfedge_const_handle>(&(ptr()->e2)) != NULL);
+    CGAL_assertion(boost::get<Halfedge_const_handle>(&(ptr()->e2)) != nullptr);
     return boost::get<Halfedge_const_handle>(ptr()->e2);
     }
   
@@ -535,7 +535,7 @@ public:
     CGAL_precondition(type() == TD_VERTEX);
     CGAL_precondition(!is_on_boundaries());
 
-    CGAL_assertion(boost::get<Point>( &(ptr()->e0)) != NULL);
+    CGAL_assertion(boost::get<Point>( &(ptr()->e0)) != nullptr);
     return boost::get<Point>( ptr()->e0 );
     }
   
@@ -545,10 +545,10 @@ public:
     CGAL_precondition(type() == TD_VERTEX);
     CGAL_precondition(is_on_boundaries());
 
-    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != NULL);
+    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != nullptr);
-    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != NULL);
+    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != nullptr);
     X_monotone_curve_2* cv_ptr = (boost::get<boost::shared_ptr<X_monotone_curve_2> >(ptr()->e2)).get();
-    CGAL_assertion(cv_ptr != NULL);
+    CGAL_assertion(cv_ptr != nullptr);
    
     Arr_curve_end ce = 
       (boost::get<unsigned char>(ptr()->e1) == CGAL_TD_CV_MIN_END) ?
@@ -563,10 +563,10 @@ public:
     CGAL_precondition(type() == TD_VERTEX);
     CGAL_precondition(is_on_boundaries());
 
-    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != NULL);
+    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != nullptr);
-    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != NULL);
+    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != nullptr);
     X_monotone_curve_2* cv_ptr = (boost::get<boost::shared_ptr<X_monotone_curve_2> >(ptr()->e2)).get();
-    CGAL_assertion(cv_ptr != NULL);
+    CGAL_assertion(cv_ptr != nullptr);
    
     Arr_curve_end ce = 
       (boost::get<unsigned char>(ptr()->e1) == CGAL_TD_CV_MIN_END) ?
@@ -580,10 +580,10 @@ public:
     CGAL_precondition(!is_active()); 
     CGAL_precondition(type() == TD_VERTEX);
 
-    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != NULL);
+    CGAL_assertion(boost::get<unsigned char>( &(ptr()->e1)) != nullptr);
-    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != NULL);
+    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != nullptr);
     X_monotone_curve_2* cv_ptr = (boost::get<boost::shared_ptr<X_monotone_curve_2> >(ptr()->e2)).get();
-    CGAL_assertion(cv_ptr != NULL);
+    CGAL_assertion(cv_ptr != nullptr);
     
     Arr_curve_end ce = 
       (boost::get<unsigned char>(ptr()->e1) == CGAL_TD_CV_MIN_END) ?
@@ -596,9 +596,9 @@ public:
   {
     CGAL_precondition(!is_active() && type() == TD_EDGE); 
     
-    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != NULL);
+    CGAL_assertion(boost::get<boost::shared_ptr<X_monotone_curve_2> >(&(ptr()->e2)) != nullptr);
     X_monotone_curve_2* cv_ptr = (boost::get<boost::shared_ptr<X_monotone_curve_2> >(ptr()->e2)).get();
-    CGAL_assertion(cv_ptr != NULL);
+    CGAL_assertion(cv_ptr != nullptr);
     return *cv_ptr;
   }
 

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_active_edge.h

@@ -200,8 +200,8 @@ public:
   {
     
     PTR = new Data
-      (Traits::empty_he_handle(), Td_map_item(0), NULL);
+      (Traits::empty_he_handle(), Td_map_item(0), nullptr);
-    //m_dag_node = NULL;
+    //m_dag_node = nullptr;
   }
    /*! Constructor given Vertex & Halfedge handles. */
   Td_active_edge (Halfedge_const_handle he ,

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_active_fictitious_vertex.h

@@ -189,7 +189,7 @@ public:
 
   Td_active_fictitious_vertex()
   {
-    PTR = new Data(Traits::empty_vtx_handle(), Traits::empty_he_handle(), NULL);
+    PTR = new Data(Traits::empty_vtx_handle(), Traits::empty_he_handle(), nullptr);
   }
 
   /*! Constructor given Vertex & Halfedge handles. */

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_active_trapezoid.h

@@ -261,7 +261,7 @@ public:
        Traits::empty_vtx_handle(),
        Traits::empty_he_handle(),
        Traits::empty_he_handle(),
-       Td_map_item(0), Td_map_item(0) , Td_map_item(0) , Td_map_item(0), NULL);
+       Td_map_item(0), Td_map_item(0) , Td_map_item(0) , Td_map_item(0), nullptr);
    
     //m_dag_node = 0;
   }

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_active_vertex.h

@@ -191,7 +191,7 @@ public:
 
   Td_active_vertex()
   {
-    PTR = new Data(Traits::empty_vtx_handle(), Traits::empty_he_handle(), NULL);
+    PTR = new Data(Traits::empty_vtx_handle(), Traits::empty_he_handle(), nullptr);
   }
 
   /*! Constructor given Vertex & Halfedge handles. */

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_inactive_edge.h

@@ -168,7 +168,7 @@ public:
   //@{
 
   /*! Constructor given Vertex & Halfedge handles. */
-  Td_inactive_edge (boost::shared_ptr<X_monotone_curve_2>& cv, Dag_node* node = NULL)
+  Td_inactive_edge (boost::shared_ptr<X_monotone_curve_2>& cv, Dag_node* node = nullptr)
   {
     PTR = new Data(cv,node);
   }
@@ -230,7 +230,7 @@ public:
   inline X_monotone_curve_2& curve() const  
   {
     X_monotone_curve_2* cv_ptr = (ptr()->cv).get();
-    CGAL_assertion(cv_ptr != NULL);
+    CGAL_assertion(cv_ptr != nullptr);
     return *cv_ptr;
   }
 

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_inactive_fictitious_vertex.h

@@ -190,7 +190,7 @@ public:
   //@{
 
   /*! Constructor given Vertex & Halfedge handles. */
-  Td_inactive_fictitious_vertex (Vertex_const_handle v_before_rem, Dag_node* node = NULL)
+  Td_inactive_fictitious_vertex (Vertex_const_handle v_before_rem, Dag_node* node = nullptr)
   {
     Curve_end v_ce(vtx_to_ce(v_before_rem));
    

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_inactive_vertex.h

@@ -169,7 +169,7 @@ public:
   //@{
 
   /*! Constructor given Vertex & Halfedge handles. */
-  Td_inactive_vertex (Vertex_const_handle v_before_rem, Dag_node* node = NULL)
+  Td_inactive_vertex (Vertex_const_handle v_before_rem, Dag_node* node = nullptr)
   {
     PTR = new Data(v_before_rem->point(), node);
   }

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Trapezoidal_decomposition_2.h

@@ -266,7 +266,7 @@ public:
       m_sep doesn't intersect any existing edges except possibly on common end
       points.
       postconditions:
-      if the rightmost trapezoid was traversed m_cur_item is set to NULL.
+      if the rightmost trapezoid was traversed m_cur_item is set to nullptr.
       remark:
       if the seperator is vertical, using the precondition assumptions it
       follows that there is exactly one trapezoid to travel.
@@ -277,9 +277,9 @@ public:
         return *this;// end reached, do nothing!
 
 #ifndef CGAL_TD_DEBUG
-      CGAL_warning(traits != NULL);
+      CGAL_warning(traits != nullptr);
 #else
-      CGAL_assertion(traits != NULL);
+      CGAL_assertion(traits != nullptr);
       CGAL_assertion(traits->is_active(m_cur_item));
       //m_cur_item should be a trapezoid or an edge
       CGAL_assertion(!traits->is_td_vertex(m_cur_item));
@@ -342,7 +342,7 @@ public:
 
         Td_active_edge e (boost::get<Td_active_edge>(m_cur_item));
         CGAL_assertion_code(Dag_node* tt = e.dag_node();)
-        CGAL_assertion(tt != NULL);
+        CGAL_assertion(tt != nullptr);
         CGAL_assertion(tt->is_inner_node());
 
         //go to next() of the current edge.
@@ -654,12 +654,12 @@ public:
     Dag_node* operator()(Td_nothing& /* t */) const
     {
       CGAL_assertion(false);
-      return NULL;
+      return nullptr;
     }
     Dag_node* operator()(Td_inactive_trapezoid& /* t */) const
     {
       CGAL_assertion(false);
-      return NULL;
+      return nullptr;
     }
 
     template < typename T >
@@ -985,7 +985,7 @@ protected:
                                            const X_monotone_curve_2& cv,
                                            Comparison_result cres) const
   {
-    CGAL_assertion(traits != NULL);
+    CGAL_assertion(traits != nullptr);
     Td_map_item& item = left_cv_end_node.get_data();
     CGAL_precondition(traits->is_td_vertex(item));
     CGAL_precondition (are_equal_end_points(Curve_end(cv,ARR_MIN_END),
@@ -1359,13 +1359,13 @@ public:
   //    const Dag_node* child;
   //    CGAL_assertion(tr_copy);
   //    tr_copy->set_rt(cur->rt() ?
-  //                    htr.find(cur->rt())->second : NULL);
+  //                    htr.find(cur->rt())->second : nullptr);
   //    tr_copy->set_rb(cur->rb() ?
-  //                    htr.find(cur->rb())->second : NULL);
+  //                    htr.find(cur->rb())->second : nullptr);
   //    tr_copy->set_lt(cur->lt() ?
-  //                    htr.find(cur->lt())->second : NULL);
+  //                    htr.find(cur->lt())->second : nullptr);
   //    tr_copy->set_lb(cur->lb() ?
-  //                    htr.find(cur->lb())->second : NULL);
+  //                    htr.find(cur->lb())->second : nullptr);
 
   //    if (cur->dag_node()->is_inner_node())
   //    {
@@ -1391,7 +1391,7 @@ public:
   */
   virtual ~Trapezoidal_decomposition_2()
   {
-    CGAL_warning(m_dag_root != NULL);
+    CGAL_warning(m_dag_root != nullptr);
     if (!m_dag_root) return;
 
     delete m_dag_root;
@@ -1616,7 +1616,7 @@ public:
 
     //the actual locate. curr is the DAG root, the traits,
     //the end point to locate,
-    //and NULL as cv ptr - indicates point location
+    //and nullptr as cv ptr - indicates point location
     lt = search_using_dag (curr, traits, ce, Halfedge_const_handle());
 
 #ifdef CGAL_TD_DEBUG
@@ -1646,7 +1646,7 @@ public:
   //  locate call may change the class
   Td_map_item& locate( Vertex_const_handle v, Locate_type& lt) const
   {
-    CGAL_precondition(traits != NULL);
+    CGAL_precondition(traits != nullptr);
     return locate(traits->vtx_to_ce(v), lt);
   }
 

Arrangement_on_surface_2/include/CGAL/Arr_point_location/Trapezoidal_decomposition_2_impl.h

@@ -278,7 +278,7 @@ split_trapezoid_by_halfedge(Dag_node& split_node,
                             Td_map_item& prev_top_tr,
                             Halfedge_const_handle he)
 {
-  CGAL_warning(traits != NULL);
+  CGAL_warning(traits != nullptr);
   CGAL_precondition(traits->is_active(split_node.get_data()));
   CGAL_precondition(traits->is_td_trapezoid(split_node.get_data()));
 
@@ -397,7 +397,7 @@ update_vtx_with_new_edge(Halfedge_const_handle he,
                          const Locate_type&
                          CGAL_precondition_code(lt))
 {
-  CGAL_assertion(traits != NULL);
+  CGAL_assertion(traits != nullptr);
   CGAL_precondition(lt == POINT);
   CGAL_precondition(traits->is_active(vtx_item));
 
@@ -441,7 +441,7 @@ insert_curve_at_vtx_using_dag(Halfedge_const_handle he,
 
   Dag_node* node = boost::apply_visitor(dag_node_visitor(), item);
 
-  CGAL_assertion(node != NULL);
+  CGAL_assertion(node != nullptr);
   CGAL_assertion(he != m_empty_he_handle);
 
 
@@ -998,7 +998,7 @@ search_using_dag(Dag_node& curr_node,
                  Comparison_result up /*=EQUAL*/) const
 {
   if (he == m_empty_he_handle)
-    return search_using_dag_with_cv(curr_node,traits,ce,NULL, up);
+    return search_using_dag_with_cv(curr_node,traits,ce,nullptr, up);
   else
     return search_using_dag_with_cv(curr_node,traits,ce,&he->curve(), up);
 }
@@ -1377,7 +1377,7 @@ typename Trapezoidal_decomposition_2<Td_traits>::Dag_node
 Trapezoidal_decomposition_2<Td_traits>::
 container2dag(Nodes_map& ar, int left, int right, int& num_of_new_nodes) const
 {
-  CGAL_warning(traits != NULL);
+  CGAL_warning(traits != nullptr);
 
   if (right > left) {
     int d = (int)std::floor((double(right+left))/2);
@@ -1414,7 +1414,7 @@ container2dag(Nodes_map& ar, int left, int right, int& num_of_new_nodes) const
     //curr_node.right_child()->set_dag_node(&curr_node.right_child());
     //curr_node->set_dag_node(&curr_node);// fake temporary node
     deactivate_vertex(curr_node); //curr_node->remove(); // mark as deleted
-    boost::apply_visitor(set_dag_node_visitor((Dag_node*)NULL),
+    boost::apply_visitor(set_dag_node_visitor((Dag_node*)nullptr),
                          curr_node.get_data());//curr_node->set_dag_node(0);
 
     return curr_node;
@@ -1462,7 +1462,7 @@ Trapezoidal_decomposition_2<Td_traits>::insert(Halfedge_const_handle he)
 
   // locate the input Halfedge end points in the Td_map_item Dag
 
-  CGAL_assertion(traits != NULL);
+  CGAL_assertion(traits != nullptr);
 
   //get the two vertices of the halfedge
   Vertex_const_handle v1 =
@@ -1565,7 +1565,7 @@ Trapezoidal_decomposition_2<Td_traits>::insert(Halfedge_const_handle he)
     }
     first_time = false;
 
-    CGAL_assertion(node != NULL);
+    CGAL_assertion(node != nullptr);
     split_trapezoid_by_halfedge(*node, old_e, old_bottom_tr, old_top_tr, he);
 
     if (node->is_inner_node()) {
@@ -1644,7 +1644,7 @@ void Trapezoidal_decomposition_2<Td_traits>::remove(Halfedge_const_handle he)
   locate_opt_empty();
 #endif
 
-  CGAL_warning(traits != NULL);
+  CGAL_warning(traits != nullptr);
 
   //calculating leftmost and rightmost curve ends of he
   const Curve_end leftmost(he, ARR_MIN_END);
@@ -1663,8 +1663,8 @@ void Trapezoidal_decomposition_2<Td_traits>::remove(Halfedge_const_handle he)
 
   if (lt1 != POINT || lt2 != POINT) return;
 
-  CGAL_warning(boost::apply_visitor(dag_node_visitor(), p1_item) != NULL);
+  CGAL_warning(boost::apply_visitor(dag_node_visitor(), p1_item) != nullptr);
-  CGAL_warning(boost::apply_visitor(dag_node_visitor(), p2_item) != NULL);
+  CGAL_warning(boost::apply_visitor(dag_node_visitor(), p2_item) != nullptr);
 
   //retrieve the Dag_nodes of the two point-degenerate trapezoid
   Dag_node& p1_node = *(boost::apply_visitor(dag_node_visitor(), p1_item));
@@ -1883,7 +1883,7 @@ void Trapezoidal_decomposition_2<Td_traits>::remove(Halfedge_const_handle he)
     removed_cv_ptr(new X_monotone_curve_2(he->curve()));
   Base_map_item_iterator last_edge_fragment_it = mid_it;
   //Base_trapezoid_iterator last_mid = mid_it;
-  Dag_node* e_node = NULL;
+  Dag_node* e_node = nullptr;
   while (!!++mid_it) {
     e_node = boost::apply_visitor(dag_node_visitor(),*last_edge_fragment_it);
     deactivate_edge(removed_cv_ptr,*e_node); //last_mid->remove();
@@ -2023,7 +2023,7 @@ vertical_ray_shoot(const Point & p,Locate_type & lt,
 //
 //  if (!traits)
 //  {
-//    CGAL_warning(traits != NULL);
+//    CGAL_warning(traits != nullptr);
 //    return;
 //  }
 //  if (!traits->are_mergeable_2_object()(cv1,cv2))
@@ -2040,7 +2040,7 @@ vertical_ray_shoot(const Point & p,Locate_type & lt,
 //    std::cerr << "\ncv1 " << cv1;
 //    std::cerr << "\ncv1 " << cv2 << std::endl;
 //  }
-//  CGAL_precondition(traits != NULL);
+//  CGAL_precondition(traits != nullptr);
 //  CGAL_precondition(traits->are_mergeable_2_object()(cv1,cv2));
 //
 //#endif
@@ -2101,8 +2101,8 @@ vertical_ray_shoot(const Point & p,Locate_type & lt,
 //
 //  CGAL_precondition(lt1==POINT && lt2==POINT);
 //  CGAL_precondition(t1.is_active() && t2.is_active());
-//  CGAL_warning(t1.dag_node() != NULL);
+//  CGAL_warning(t1.dag_node() != nullptr);
-//  CGAL_warning(t2.dag_node() != NULL);
+//  CGAL_warning(t2.dag_node() != nullptr);
 //
 //#endif
 //  m_before_split.m_cv_before_split = cv;
@@ -2221,8 +2221,8 @@ vertical_ray_shoot(const Point & p,Locate_type & lt,
 //
 //  //define the left halfedge and the right halfedge, according
 //  //  to the splitting point
-//  //Halfedge_const_handle* p_left_he  = NULL;
+//  //Halfedge_const_handle* p_left_he  = nullptr;
-//  //Halfedge_const_handle* p_right_he = NULL;
+//  //Halfedge_const_handle* p_right_he = nullptr;
 //  Halfedge_const_handle left_he  = he2;
 //  Halfedge_const_handle right_he = he1;
 //
@@ -2592,7 +2592,7 @@ merge_edge(Halfedge_const_handle he1,
   const X_monotone_curve_2& cv2 = he2->curve();
 
   if (!traits) {
-    CGAL_warning(traits != NULL);
+    CGAL_warning(traits != nullptr);
     return;
   }
   if (!traits->are_mergeable_2_object() (cv1, cv2)) {
@@ -2645,10 +2645,10 @@ merge_edge(Halfedge_const_handle he1,
   Td_map_item rightp_item = locate(rightmost, lt2);
   Td_map_item mrgp_item = locate(ce, lt);
 
-  //varifying that all trapezoids are not NULL and are of type POINT
+  //varifying that all trapezoids are not nullptr and are of type POINT
-  CGAL_warning(boost::apply_visitor(dag_node_visitor(), leftp_item) != NULL);
+  CGAL_warning(boost::apply_visitor(dag_node_visitor(), leftp_item) != nullptr);
-  CGAL_warning(boost::apply_visitor(dag_node_visitor(), rightp_item)!= NULL);
+  CGAL_warning(boost::apply_visitor(dag_node_visitor(), rightp_item)!= nullptr);
-  CGAL_warning(boost::apply_visitor(dag_node_visitor(), mrgp_item)  != NULL);
+  CGAL_warning(boost::apply_visitor(dag_node_visitor(), mrgp_item)  != nullptr);
 
   //define the left curve and the right curve, according
   //  to the common point (that is merged)
@@ -2832,7 +2832,7 @@ longest_query_path_length_rec(bool minus_inf, Dag_node& min_node,
                               bool plus_inf, Dag_node& max_node,
                               Dag_node& node)
 {
-  //if NULL
+  //if nullptr
   if (node.is_null())  return 0;
 
   //if not valid range or empty return 0

Arrangement_on_surface_2/include/CGAL/Arr_polycurve_traits_2.h

@@ -849,7 +849,7 @@ public:
           for (size_t i = 0; i < int_seg.size(); ++i) {
             const X_monotone_subcurve_2* x_seg =
               CGAL::object_cast<X_monotone_subcurve_2> (&(int_seg[i]));
-            if (x_seg != NULL) {
+            if (x_seg != nullptr) {
               X_monotone_subcurve_2 seg = *x_seg;
 
               // If for some reason the subcurve intersection
@@ -861,7 +861,7 @@ public:
 
             const Point_2_pair* p_ptr =
               CGAL::object_cast<Point_2_pair>(&(int_seg[i]));
-            if (p_ptr != NULL) {
+            if (p_ptr != nullptr) {
               // Any point that is not equal to the max_vertex of the
               // subcurve should be inserted into oi.
               // The max_vertex of the current subcurve (if intersecting)

Arrangement_on_surface_2/include/CGAL/Arr_rat_arc/Cache.h

@@ -108,7 +108,7 @@ public:
 
 public:
   Cache() :
-    _rat_func_map_watermark(128), _rat_pair_map_watermark(128), _ak_ptr(NULL){};
+    _rat_func_map_watermark(128), _rat_pair_map_watermark(128), _ak_ptr(nullptr){};
 
   void initialize(Algebraic_kernel_d_1* ak_ptr)
   {
@@ -165,7 +165,7 @@ public:
   const Rational_function& get_rational_function(const Polynomial_1& numer,
                                                  const Polynomial_1& denom) const
   {
-    CGAL_precondition (_ak_ptr != NULL);
+    CGAL_precondition (_ak_ptr != nullptr);
     Rational_function_key key  = get_key(numer,denom);
 
     //look if element exists in cache already
@@ -204,7 +204,7 @@ public:
   const Rational_function_pair get_rational_pair(const Rational_function& f, 
                                                  const Rational_function& g) const
   {
-    CGAL_precondition (_ak_ptr != NULL);
+    CGAL_precondition (_ak_ptr != nullptr);
     CGAL_precondition(!(f==g));
     Rational_function_canonicalized_pair_key key  = get_key(f,g);
     bool is_opposite = (f.id() < g.id()) ? false : true ; 

Arrangement_on_surface_2/include/CGAL/Arr_rat_arc/Rational_function.h

@@ -47,7 +47,7 @@ public:
   typedef typename Base::Solve_1                       Solve_1;
     
 public:
-  Rational_function_rep() : _ak_ptr(NULL){}
+  Rational_function_rep() : _ak_ptr(nullptr){}
   Rational_function_rep(const Polynomial_1& numer,
                         const Polynomial_1& denom, 
                         Algebraic_kernel_d_1* ak_ptr):
@@ -117,7 +117,7 @@ public:
 private:
   void initialize()
   {
-    CGAL_precondition(_ak_ptr != NULL);
+    CGAL_precondition(_ak_ptr != nullptr);
     CGAL_precondition(CGAL::is_zero(_denom) == false);
     if (CGAL::is_zero(_numer))
     {

Arrangement_on_surface_2/include/CGAL/Arr_rat_arc/Rational_function_canonicalized_pair.h

@@ -59,7 +59,7 @@ public:
                                            Algebraic_kernel_d_1* ak_ptr)
     :_f(f),_g(g),_ak_ptr(ak_ptr)
   {
-    CGAL_precondition(_ak_ptr != NULL);
+    CGAL_precondition(_ak_ptr != nullptr);
     //canonicalized representation
     if ( !(f.id() < g.id()) ) 
       std::swap(_f,_g);

Arrangement_on_surface_2/include/CGAL/Arr_rat_arc/Singleton.h

@@ -39,14 +39,14 @@ public:
   {
     if(!m_pInstance) 
       m_pInstance = new T;
-    CGAL_assertion(m_pInstance !=NULL);
+    CGAL_assertion(m_pInstance !=nullptr);
     return m_pInstance;
   }
       
   static void DestroyInstance()
   {
     delete m_pInstance;
-    m_pInstance = NULL;
+    m_pInstance = nullptr;
   };
 private:
   Singleton();          // ctor hidden
@@ -55,7 +55,7 @@ private:
   static T* m_pInstance;
 };
 
-template <class T> T* Singleton<T>::m_pInstance=NULL;
+template <class T> T* Singleton<T>::m_pInstance=nullptr;
 
 }   // namespace Arr_rational_arc
 }   //namespace CGAL { 

Arrangement_on_surface_2/include/CGAL/Arr_segment_traits_2.h

@@ -766,7 +766,7 @@ public:
       // Check if we have a single intersection point.
       const Point_2  *ip = object_cast<Point_2> (&obj);
 
-      if (ip != NULL) {
+      if (ip != nullptr) {
         // Check if the intersection point ip lies on both segments.
         const bool    ip_on_cv1 = cv1.is_vertical() ? cv1.is_in_y_range(*ip) :
                                                       cv1.is_in_x_range(*ip);

Arrangement_on_surface_2/include/CGAL/Arr_simple_point_location.h

@@ -96,9 +96,9 @@ protected:
 public:
   /*! Default constructor. */
   Arr_simple_point_location() : 
-    m_arr(NULL),
+    m_arr(nullptr),
-    m_geom_traits(NULL),
+    m_geom_traits(nullptr),
-    m_topol_traits(NULL)
+    m_topol_traits(nullptr)
   {}
         
   /*! Constructor given an arrangement. */
@@ -122,9 +122,9 @@ public:
   /*! Detach from the current arrangement object. */
   void detach()
   {
-    m_arr = NULL;
+    m_arr = nullptr;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
-    m_topol_traits = NULL;
+    m_topol_traits = nullptr;
   }
  
   /*!

Arrangement_on_surface_2/include/CGAL/Arr_spherical_gaussian_map_3/Arr_polyhedral_sgm.h

@@ -524,7 +524,7 @@ public:
   /*! Constructor */
   Arr_polyhedral_sgm_initializer(PolyhedralSgm& sgm) :
     Base(sgm),
-    m_visitor(NULL),
+    m_visitor(nullptr),
     m_marked_vertex_index(0),
     m_marked_edge_index(0),
     m_marked_facet_index(0)
@@ -538,7 +538,7 @@ public:
    * \param visitor
    * \pre The polyhedron polyhedron does not have coplanar facets.
    */
-  void operator()(Polyhedron& polyhedron, Visitor* visitor = NULL)
+  void operator()(Polyhedron& polyhedron, Visitor* visitor = nullptr)
   {
 #if 0
     std::copy(polyhedron.points_begin(), polyhedron.points_end(),
@@ -568,7 +568,7 @@ public:
                   const CoordIndexIter indices_begin,
                   const CoordIndexIter indices_end,
                   size_type num_facets,
-                  Visitor* visitor = NULL)
+                  Visitor* visitor = nullptr)
   {
     m_visitor = visitor;
 

Arrangement_on_surface_2/include/CGAL/Arr_spherical_gaussian_map_3/Arr_polyhedral_sgm_polyhedron_3.h

@@ -148,7 +148,7 @@ public:
   typedef typename Base::Plane                        Plane;
 
   /*! Constructor */
-  Arr_polyhedral_sgm_polyhedron_3_face() : m_vertex(NULL), m_marked(false) {}
+  Arr_polyhedral_sgm_polyhedron_3_face() : m_vertex(nullptr), m_marked(false) {}
 
   /*! Obtain the mutable plane. Delegate */
   Plane & plane() { return Base::plane(); }

Arrangement_on_surface_2/include/CGAL/Arr_spherical_gaussian_map_3/Arr_transform_on_sphere.h

@@ -213,7 +213,7 @@ void Arr_transform_on_sphere(Arrangement & arr,
 		ind = ARR_MAX_END;
 
       // Check if it was already added.
-      if (topol_traits->discontinuity_vertex(havc->curve(), ind)== NULL &&
+      if (topol_traits->discontinuity_vertex(havc->curve(), ind)== nullptr &&
           topol_traits->south_pole() != &(*havc->target()) &&
           topol_traits->north_pole() != &(*havc->target()) )
       {

Arrangement_on_surface_2/include/CGAL/Arr_spherical_topology_traits_2.h

@@ -139,7 +139,7 @@ private:
   //! A container of boundary vertices.
   struct Vertex_key_comparer {
     /*! Construct default */
-    Vertex_key_comparer() : m_geom_traits(NULL) {}
+    Vertex_key_comparer() : m_geom_traits(nullptr) {}
 
     /*! Construct */
     Vertex_key_comparer(const Gt_adaptor_2* geom_traits) :
@@ -297,7 +297,7 @@ public:
   Vertex* north_pole() { return m_north_pole; }
 
   /*! Obtain a vertex on the line of discontinuity that corresponds to
-   *  the given curve-end (or return NULL if no such vertex exists).
+   *  the given curve-end (or return nullptr if no such vertex exists).
    */
   Vertex* discontinuity_vertex(const X_monotone_curve_2 xc, Arr_curve_end ind)
   {
@@ -305,7 +305,7 @@ public:
       m_geom_traits->construct_min_vertex_2_object()(xc) :
       m_geom_traits->construct_max_vertex_2_object()(xc);
     typename Vertex_map::iterator it = m_boundary_vertices.find(key);
-    return (it != m_boundary_vertices.end()) ? it->second : NULL;
+    return (it != m_boundary_vertices.end()) ? it->second : nullptr;
   }
   //@}
 
@@ -546,7 +546,7 @@ public:
   {
     // There are no fictitious halfedges:
     CGAL_error();
-    return NULL;
+    return nullptr;
   }
 
   /*! Determine whether the given face is unbounded.

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_bounded_planar_topology_traits_2_impl.h

@@ -71,7 +71,7 @@ void Arr_bounded_planar_topology_traits_2<GeometryTraits_2, Dcel_>::
 dcel_updated()
 {
   // Go over the DCEL faces and locate the unbounded face.
-  unb_face = NULL;
+  unb_face = nullptr;
   typename Dcel::Face_iterator fit = this->m_dcel.faces_begin();
   for (; fit != this->m_dcel.faces_end(); ++fit) {
     if (fit->is_unbounded()) {
@@ -79,7 +79,7 @@ dcel_updated()
       break;
     }
   }
-  CGAL_assertion(unb_face != NULL);
+  CGAL_assertion(unb_face != nullptr);
 }
 
 } // namespace CGAL

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_inc_insertion_zone_visitor.h

@@ -79,8 +79,8 @@ public:
 
   /*! Constructor. */
   Arr_inc_insertion_zone_visitor () :
-    p_arr (NULL),
+    p_arr (nullptr),
-    geom_traits (NULL),
+    geom_traits (nullptr),
     invalid_v (),
     invalid_he ()
   {}

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_planar_topology_traits_base_2.h

@@ -110,9 +110,9 @@ public:
     // Clear the DCEL.
     m_dcel.delete_all();
 
-    if (m_own_geom_traits && (m_geom_traits != NULL)) {
+    if (m_own_geom_traits && (m_geom_traits != nullptr)) {
       delete m_geom_traits;
-      m_geom_traits = NULL;
+      m_geom_traits = nullptr;
     }
   }
   //@}
@@ -247,9 +247,9 @@ Arr_planar_topology_traits_base_2<GeomTraits, Dcel_>::assign(const Self& other)
   m_dcel.assign(other.m_dcel);
 
   // Take care of the traits object.
-  if (m_own_geom_traits && (m_geom_traits != NULL)) {
+  if (m_own_geom_traits && (m_geom_traits != nullptr)) {
     delete m_geom_traits;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
   }
 
   if (other.m_own_geom_traits) m_geom_traits = new Traits_adaptor_2;
@@ -265,8 +265,8 @@ template <typename GeomTraits, typename Dcel_>
 bool Arr_planar_topology_traits_base_2<GeomTraits, Dcel_>::
 is_in_face(const Face* f, const Point_2& p, const Vertex* v) const
 {
-  CGAL_precondition((v == NULL) || ! v->has_null_point());
+  CGAL_precondition((v == nullptr) || ! v->has_null_point());
-  CGAL_precondition((v == NULL) ||
+  CGAL_precondition((v == nullptr) ||
                     m_geom_traits->equal_2_object()(p, v->point()));
 
   // In case the face is unbounded and has no outer ccbs, this is the single
@@ -310,7 +310,7 @@ is_in_face(const Face* f, const Point_2& p, const Vertex* v) const
 
   do {
     // Compare p to the target vertex of the current halfedge.
-    // If the vertex v associated with p (if v is given and is not NULL)
+    // If the vertex v associated with p (if v is given and is not nullptr)
     // on the boundary of the component, p is obviously not in the interior
     // the component.
     if (curr->vertex() == v) return false;

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_spherical_construction_helper.h

@@ -114,7 +114,7 @@ public:
   Arr_spherical_construction_helper(Arrangement_2* arr) :
     m_top_traits(arr->topology_traits()),
     m_arr_access(*arr),
-    m_he_ind_map_p(NULL)
+    m_he_ind_map_p(nullptr)
   {}
 
   /*! Destructor. */
@@ -172,7 +172,7 @@ public:
    */
   void splice_indices_list(Halfedge_handle he)
   {
-    CGAL_assertion(m_he_ind_map_p != NULL);
+    CGAL_assertion(m_he_ind_map_p != nullptr);
     Indices_list& list_ref = (*m_he_ind_map_p)[he];
     list_ref.splice(list_ref.end(), m_subcurves_at_nf);
   }

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_spherical_topology_traits_2_impl.h

@@ -36,9 +36,9 @@ namespace CGAL {
 template <typename GeomTraits, typename Dcel>
 Arr_spherical_topology_traits_2<GeomTraits, Dcel>::
 Arr_spherical_topology_traits_2() :
-  m_spherical_face(NULL),
+  m_spherical_face(nullptr),
-  m_north_pole(NULL),
+  m_north_pole(nullptr),
-  m_south_pole(NULL),
+  m_south_pole(nullptr),
   m_own_geom_traits(true)
 {
   m_geom_traits = new Gt_adaptor_2;
@@ -49,9 +49,9 @@ Arr_spherical_topology_traits_2() :
 template <typename GeomTraits, typename Dcel>
 Arr_spherical_topology_traits_2<GeomTraits, Dcel>::
 Arr_spherical_topology_traits_2(const Geometry_traits_2* traits) :
-  m_spherical_face(NULL),
+  m_spherical_face(nullptr),
-  m_north_pole(NULL),
+  m_north_pole(nullptr),
-  m_south_pole(NULL),
+  m_south_pole(nullptr),
   m_own_geom_traits(false)
 {
   m_geom_traits = static_cast<const Gt_adaptor_2*>(traits);
@@ -66,9 +66,9 @@ Arr_spherical_topology_traits_2<GeomTraits, Dcel>::
   // Clear the DCEL.
   m_dcel.delete_all();
 
-  if (m_own_geom_traits && (m_geom_traits != NULL)) {
+  if (m_own_geom_traits && (m_geom_traits != nullptr)) {
     delete m_geom_traits;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
   }
 }
 
@@ -82,9 +82,9 @@ assign(const Self& other)
   m_dcel.assign(other.m_dcel);
 
   // Take care of the traits object.
-  if (m_own_geom_traits && m_geom_traits != NULL) {
+  if (m_own_geom_traits && m_geom_traits != nullptr) {
     delete m_geom_traits;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
   }
 
   if (other.m_own_geom_traits) {
@@ -109,8 +109,8 @@ void Arr_spherical_topology_traits_2<GeomTraits_, Dcel_>::dcel_updated()
   // Go over the DCEL vertices and locate the south and north pole (if any)
   // and any other vertex on the line of discontinuity.
 
-  m_north_pole = NULL;
+  m_north_pole = nullptr;
-  m_south_pole = NULL;
+  m_south_pole = nullptr;
   m_boundary_vertices.clear();
 
   typename Dcel::Vertex_iterator vit = this->m_dcel.vertices_begin();
@@ -129,17 +129,17 @@ void Arr_spherical_topology_traits_2<GeomTraits_, Dcel_>::dcel_updated()
   // Go over the DCEL faces and locate the spherical face, which is the only
   // face with no outer CCB.
 
-  m_spherical_face = NULL;
+  m_spherical_face = nullptr;
   typename Dcel::Face_iterator fit = this->m_dcel.faces_begin();
   for (; fit != this->m_dcel.faces_end(); ++fit) {
     if (fit->number_of_outer_ccbs() == 0) {
-      CGAL_assertion(m_spherical_face == NULL);
+      CGAL_assertion(m_spherical_face == nullptr);
 
       m_spherical_face = &(*fit);
       break;
     }
   }
-  CGAL_assertion(m_spherical_face != NULL);
+  CGAL_assertion(m_spherical_face != nullptr);
 }
 
 /*! \brief initializes an empty DCEL structure. */
@@ -156,8 +156,8 @@ void Arr_spherical_topology_traits_2<GeomTraits, Dcel>::init_dcel()
   m_spherical_face->set_unbounded(false);
   m_spherical_face->set_fictitious(false);
 
-  m_north_pole = NULL;
+  m_north_pole = nullptr;
-  m_south_pole = NULL;
+  m_south_pole = nullptr;
 }
 
 /*! \brief determines whether a point lies in the interior of a given face. */
@@ -166,8 +166,8 @@ bool Arr_spherical_topology_traits_2<GeomTraits, Dcel>::
 is_in_face(const Face* f, const Point_2& p, const Vertex* v) const
 {
   // std::cout << "is_in_face()" << std::endl;
-  CGAL_precondition((v == NULL) || !v->has_null_point());
+  CGAL_precondition((v == nullptr) || !v->has_null_point());
-  CGAL_precondition((v == NULL) ||
+  CGAL_precondition((v == nullptr) ||
                     m_geom_traits->equal_2_object()(p, v->point()));
 
   /* There is always one face that contains everything else. It has no
@@ -183,12 +183,12 @@ is_in_face(const Face* f, const Point_2& p, const Vertex* v) const
             << std::endl;
 #endif
   if (f->number_of_outer_ccbs() == 0) return true;
-  if (((v != NULL) && (v->parameter_space_in_y() == ARR_TOP_BOUNDARY)) ||
+  if (((v != nullptr) && (v->parameter_space_in_y() == ARR_TOP_BOUNDARY)) ||
       (m_geom_traits->parameter_space_in_y_2_object()(p) == ARR_TOP_BOUNDARY))
     return false;
 
   /*! \todo a temporary test
-   * if (((v != NULL) && (v->parameter_space_in_y() == ARR_BOTTOM_BOUNDARY)) ||
+   * if (((v != nullptr) && (v->parameter_space_in_y() == ARR_BOTTOM_BOUNDARY)) ||
    *   (p.is_min_boundary()))
    * return false;
    */
@@ -536,12 +536,12 @@ place_boundary_vertex(Face* /* f */,
 {
   // std::cout << "place_boundary_vertex()" << std::endl;
   if (ps_y == ARR_BOTTOM_BOUNDARY) {
-    if (m_south_pole == NULL) return Object();
+    if (m_south_pole == nullptr) return Object();
     return CGAL::make_object(m_south_pole);
   }
 
   if (ps_y == ARR_TOP_BOUNDARY) {
-    if (m_north_pole == NULL) return Object();
+    if (m_north_pole == nullptr) return Object();
     return CGAL::make_object(m_north_pole);
   }
 
@@ -608,18 +608,18 @@ locate_curve_end(const X_monotone_curve_2& xc, Arr_curve_end ind,
     // In case the curve end coincides with the north pole, return the vertex
     // representing the north pole, if one exists. Otherwise, return the face
     // containing this pole (the spherical face).
-    if (m_north_pole != NULL) return CGAL::make_object(m_north_pole);
+    if (m_north_pole != nullptr) return CGAL::make_object(m_north_pole);
     return CGAL::make_object(m_spherical_face);
   }
 
   typename Vertex_map::iterator it;
-  Vertex* v = NULL;
+  Vertex* v = nullptr;
 
   if (ps_y == ARR_BOTTOM_BOUNDARY) {
     // In case the curve end coincides with the south pole, return the vertex
     // representing the south pole, if one exists. Otherwise, search for the
     // face containing this pole.
-    if (m_south_pole != NULL) return CGAL::make_object(m_south_pole);
+    if (m_south_pole != nullptr) return CGAL::make_object(m_south_pole);
     it = m_boundary_vertices.begin();
   }
   else {
@@ -655,7 +655,7 @@ locate_curve_end(const X_monotone_curve_2& xc, Arr_curve_end ind,
 template <typename GeomTraits, typename Dcel>
 bool Arr_spherical_topology_traits_2<GeomTraits, Dcel>::
 is_redundant(const Vertex* v) const
-{ return (v->halfedge() == NULL); }
+{ return (v->halfedge() == nullptr); }
 
 /* \brief erases a given redundant vertex */
 template <typename GeomTraits, typename Dcel>
@@ -665,17 +665,17 @@ erase_redundant_vertex(Vertex* v)
 {
   const Arr_parameter_space ps_y = v->parameter_space_in_y();
   if (ps_y == ARR_BOTTOM_BOUNDARY) {
-    m_south_pole = NULL;
+    m_south_pole = nullptr;
-    return NULL;
+    return nullptr;
   }
   if (ps_y == ARR_TOP_BOUNDARY) {
-    m_north_pole = NULL;
+    m_north_pole = nullptr;
-    return NULL;
+    return nullptr;
   }
   CGAL_assertion_code(Arr_parameter_space ps_x = v->parameter_space_in_x());
   CGAL_assertion(ps_x != ARR_INTERIOR);
   m_boundary_vertices.erase(v->point());
-  return NULL;
+  return nullptr;
 }
 
 /*! \brief obtains the curve associated with a boundary vertex */
@@ -703,12 +703,12 @@ _locate_around_vertex_on_discontinuity(Vertex* v,
                                        Arr_curve_end ind) const
 {
   // If the vertex is isolated, there is no predecssor halfedge.
-  if (v->is_isolated()) return NULL;
+  if (v->is_isolated()) return nullptr;
 
   // Get the first incident halfedge around v and the next halfedge.
   Halfedge* first = v->halfedge();
   Halfedge* curr = first;
-  CGAL_assertion(curr != NULL);
+  CGAL_assertion(curr != nullptr);
   Halfedge* next = curr->next()->opposite();
 
   // If is only one halfedge incident to v, return this halfedge as xc's
@@ -756,12 +756,12 @@ _locate_around_pole(Vertex* v,
 
   // std::cout << "locate_around_pole() " << ind << std::endl;
   // If the vertex is isolated, return a null halfedge:
-  if (v->is_isolated()) return NULL;
+  if (v->is_isolated()) return nullptr;
 
   // Get the first incident halfedge around v and the next halfedge:
   Halfedge* first = v->halfedge();
   Halfedge* curr = first;
-  CGAL_assertion(curr != NULL);
+  CGAL_assertion(curr != nullptr);
   Halfedge* next = curr->next()->opposite();
 
   // If there is only one halfedge, it is the predecessor, return it:
@@ -809,7 +809,7 @@ _locate_around_pole(Vertex* v,
 
   // We sould never reach here:
   CGAL_error();
-  return NULL;
+  return nullptr;
 }
 
 /*! \brief Return the face that lies below the given vertex, which lies
@@ -826,7 +826,7 @@ _face_below_vertex_on_discontinuity(Vertex* v) const
   // Get the first incident halfedge around v and the next halfedge.
   Halfedge* first = v->halfedge();
   Halfedge* curr = first;
-  CGAL_assertion(curr != NULL);
+  CGAL_assertion(curr != nullptr);
   Halfedge* next = curr->next()->opposite();
 
   // If there is only one halfedge incident to v, return its incident face.
@@ -842,8 +842,8 @@ _face_below_vertex_on_discontinuity(Vertex* v) const
   typename Gt_adaptor_2::Compare_y_at_x_left_2  cmp_y_at_x_op_left =
     m_geom_traits->compare_y_at_x_left_2_object();
 
-  Halfedge* lowest_left = NULL;
+  Halfedge* lowest_left = nullptr;
-  Halfedge* top_right = NULL;
+  Halfedge* top_right = nullptr;
 
   do {
     // Check whether the current halfedge is defined to the left or to the
@@ -851,7 +851,7 @@ _face_below_vertex_on_discontinuity(Vertex* v) const
     if (curr->direction() == ARR_LEFT_TO_RIGHT) {
       // The curve associated with the current halfedge is defined to the left
       // of v.
-      if (lowest_left == NULL ||
+      if (lowest_left == nullptr ||
           cmp_y_at_x_op_left(curr->curve(), lowest_left->curve(), v->point())
           == SMALLER)
       {
@@ -861,7 +861,7 @@ _face_below_vertex_on_discontinuity(Vertex* v) const
     else {
       // The curve associated with the current halfedge is defined to the right
       // of v.
-      if (top_right == NULL ||
+      if (top_right == nullptr ||
           cmp_y_at_x_op_right(curr->curve(), top_right->curve(), v->point()) ==
           LARGER)
       {
@@ -878,7 +878,7 @@ _face_below_vertex_on_discontinuity(Vertex* v) const
   // right. Note that as the halfedge we located has v as its target, we now
   // have to return its twin.
   first =
-    (lowest_left != NULL) ? lowest_left->opposite() : top_right->opposite();
+    (lowest_left != nullptr) ? lowest_left->opposite() : top_right->opposite();
   // std::cout << "first: " << first->opposite()->vertex()->point() << " => "
   //           << first->vertex()->point() << std::endl;
 

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_spherical_vert_decomp_helper.h

@@ -114,14 +114,14 @@ public:
   void Arr_spherical_vert_decomp_helper<Tr, Arr, Evnt, Sbcv>::before_sweep()
 {
   // Get the north pole and the face that intially contains it.
-  m_valid_north_pole = (m_top_traits->north_pole() != NULL);
+  m_valid_north_pole = (m_top_traits->north_pole() != nullptr);
   if (m_valid_north_pole)
     m_north_pole = Vertex_const_handle (m_top_traits->north_pole());
 
   m_north_face = Face_const_handle (m_top_traits->spherical_face());
 
   // Get the south pole and the face that intially contains it.
-  m_valid_south_pole = (m_top_traits->south_pole() != NULL);
+  m_valid_south_pole = (m_top_traits->south_pole() != nullptr);
   if (m_valid_south_pole)
     m_south_pole = Vertex_const_handle (m_top_traits->south_pole());
 

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_unb_planar_construction_helper.h

@@ -116,9 +116,9 @@ public:
   Arr_unb_planar_construction_helper(Arrangement_2* arr) :
     m_top_traits(arr->topology_traits()),
     m_arr_access(*arr),
-    m_prev_minus_inf_x_event(NULL),
+    m_prev_minus_inf_x_event(nullptr),
-    m_prev_plus_inf_y_event(NULL),
+    m_prev_plus_inf_y_event(nullptr),
-    m_he_ind_map_p(NULL)
+    m_he_ind_map_p(nullptr)
   {}
 
   /*! Destructor. */
@@ -155,7 +155,7 @@ public:
     // The last event at y = +oo may be deallocated if it has no incident
     // right subcurves, so we should not keep a pointer to it.
     if (event == m_prev_plus_inf_y_event)
-      m_prev_plus_inf_y_event = NULL;
+      m_prev_plus_inf_y_event = nullptr;
   }
   //@}
 
@@ -278,7 +278,7 @@ before_handle_event(Event* event)
 
     // Update the incident halfedge of the previous vertex at x = -oo
     // (m_lh used to be incident to it, but now we have split it).
-    if (m_prev_minus_inf_x_event != NULL)
+    if (m_prev_minus_inf_x_event != nullptr)
       m_prev_minus_inf_x_event->set_halfedge_handle(m_lh->next());
     m_prev_minus_inf_x_event = event;
     return;
@@ -311,13 +311,13 @@ before_handle_event(Event* event)
 
       // Update the incident halfedge of the previous vertex at y = +oo
       // (m_th used to be incident to it, but now we have split it).
-      if (m_prev_plus_inf_y_event != NULL)
+      if (m_prev_plus_inf_y_event != nullptr)
         m_prev_plus_inf_y_event->set_halfedge_handle(m_th->next());
       m_prev_plus_inf_y_event = event;
 
       // Associate all curve indices of subcurves that "see" m_th from
       // below with the left portion of the split halfedge (m_th->next()).
-      if (m_he_ind_map_p != NULL)
+      if (m_he_ind_map_p != nullptr)
       {
         Indices_list& list_ref = (*m_he_ind_map_p)[m_th->next()];
         list_ref.clear();

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_unb_planar_insertion_helper.h

@@ -187,7 +187,7 @@ before_handle_event(Event* event)
   if (ps_x == ARR_LEFT_BOUNDARY) {
     // The event lies on the left fictitious halfedge.
     this->m_lh = this->m_lh->twin()->next()->twin();
-    this->m_prev_minus_inf_x_event = NULL;
+    this->m_prev_minus_inf_x_event = nullptr;
   }
   else if (ps_x == ARR_RIGHT_BOUNDARY) {
     // The event lies on the right fictitious halfedge.
@@ -204,7 +204,7 @@ before_handle_event(Event* event)
       // The event lies on the top fictitious halfedge.
       CGAL_assertion (ps_y == ARR_TOP_BOUNDARY);
       this->m_th = this->m_th->twin()->next()->twin();
-      this->m_prev_plus_inf_y_event = NULL;
+      this->m_prev_plus_inf_y_event = nullptr;
     }
   }
 }

Arrangement_on_surface_2/include/CGAL/Arr_topology_traits/Arr_unb_planar_topology_traits_2_impl.h

@@ -40,12 +40,12 @@ template <typename GeomTraits, typename Dcel_>
 Arr_unb_planar_topology_traits_2<GeomTraits, Dcel_>::
 Arr_unb_planar_topology_traits_2():
   Base(),
-  v_bl(NULL),
+  v_bl(nullptr),
-  v_tl(NULL),
+  v_tl(nullptr),
-  v_br(NULL),
+  v_br(nullptr),
-  v_tr(NULL),
+  v_tr(nullptr),
   n_inf_verts(0),
-  fict_face(NULL)
+  fict_face(nullptr)
 {}
 
 //-----------------------------------------------------------------------------
@@ -55,12 +55,12 @@ template <typename GeomTraits, typename Dcel_>
 Arr_unb_planar_topology_traits_2<GeomTraits, Dcel_>::
 Arr_unb_planar_topology_traits_2 (const Geometry_traits_2 * geom_traits) :
   Base (geom_traits),
-  v_bl (NULL),
+  v_bl (nullptr),
-  v_tl (NULL),
+  v_tl (nullptr),
-  v_br (NULL),
+  v_br (nullptr),
-  v_tr (NULL),
+  v_tr (nullptr),
   n_inf_verts (0),
-  fict_face (NULL)
+  fict_face (nullptr)
 {}
 
 //-----------------------------------------------------------------------------
@@ -89,7 +89,7 @@ void Arr_unb_planar_topology_traits_2<GeomTraits, Dcel_>::dcel_updated ()
   typename Dcel::Vertex_iterator       vit;
   Halfedge                            *first_he, *next_he;
 
-  v_bl = v_tl = v_br = v_tr = NULL;
+  v_bl = v_tl = v_br = v_tr = nullptr;
   n_inf_verts = 0;
   for (vit = this->m_dcel.vertices_begin();
        vit != this->m_dcel.vertices_end(); ++vit)
@@ -123,23 +123,23 @@ void Arr_unb_planar_topology_traits_2<GeomTraits, Dcel_>::dcel_updated ()
         CGAL_error();
     }
   }
-  CGAL_assertion(v_bl != NULL && v_tl != NULL && v_br != NULL && v_tr != NULL);
+  CGAL_assertion(v_bl != nullptr && v_tl != nullptr && v_br != nullptr && v_tr != nullptr);
 
   // Go over the DCEL faces and locate the fictitious face.
   typename Dcel::Face_iterator         fit;
 
-  fict_face = NULL;
+  fict_face = nullptr;
   for (fit = this->m_dcel.faces_begin();
        fit != this->m_dcel.faces_end(); ++fit)
   {
     if (fit->is_fictitious())
     {
-      CGAL_assertion (fict_face == NULL);
+      CGAL_assertion (fict_face == nullptr);
 
       fict_face = &(*fit);
     }
   }
-  CGAL_assertion (fict_face != NULL);
+  CGAL_assertion (fict_face != nullptr);
 
   return;
 }
@@ -200,10 +200,10 @@ void Arr_unb_planar_topology_traits_2<GeomTraits, Dcel_>::init_dcel ()
   Inner_ccb          *ic = this->m_dcel.new_inner_ccb();
   Face               *in_f = this->m_dcel.new_face();
 
-  he1->set_curve (NULL);
+  he1->set_curve (nullptr);
-  he2->set_curve (NULL);
+  he2->set_curve (nullptr);
-  he3->set_curve (NULL);
+  he3->set_curve (nullptr);
-  he4->set_curve (NULL);
+  he4->set_curve (nullptr);
 
   he1->set_next (he2);        he1_t->set_next (he4_t);
   he2->set_next (he3);        he4_t->set_next (he3_t);
@@ -272,7 +272,7 @@ are_equal(const Vertex *v,
     Arr_curve_end                  v_ind;
     const X_monotone_curve_2  *v_cv = _curve (v, v_ind);
 
-    if (v_cv == NULL)
+    if (v_cv == nullptr)
       return (v->parameter_space_in_x() == ps_x &&
               v->parameter_space_in_y() == ps_y);
 
@@ -287,7 +287,7 @@ are_equal(const Vertex *v,
     Arr_curve_end                  v_ind;
     const X_monotone_curve_2  *v_cv = _curve (v, v_ind);
 
-    if (v_cv == NULL)
+    if (v_cv == nullptr)
       return (v->parameter_space_in_x() == ARR_INTERIOR &&
               v->parameter_space_in_y() == ps_y);
 
@@ -555,23 +555,23 @@ erase_redundant_vertex (Vertex *v)
 
   // Keep pointers to the components that contain two halfedges he3 and he2,
   // pointing at the end vertices of the merged halfedge.
-  Inner_ccb   *ic1 = (he3->is_on_inner_ccb()) ? he3->inner_ccb() : NULL;
+  Inner_ccb   *ic1 = (he3->is_on_inner_ccb()) ? he3->inner_ccb() : nullptr;
-  Outer_ccb   *oc1 = (ic1 == NULL) ? he3->outer_ccb() : NULL;
+  Outer_ccb   *oc1 = (ic1 == nullptr) ? he3->outer_ccb() : nullptr;
-  Inner_ccb   *ic2 = (he4->is_on_inner_ccb()) ? he4->inner_ccb() : NULL;
+  Inner_ccb   *ic2 = (he4->is_on_inner_ccb()) ? he4->inner_ccb() : nullptr;
-  Outer_ccb   *oc2 = (ic2 == NULL) ? he4->outer_ccb() : NULL;
+  Outer_ccb   *oc2 = (ic2 == nullptr) ? he4->outer_ccb() : nullptr;
 
   // As he1 and he2 will evetually represent the merged edge, while he3 and he4
   // will be deleted, check if the deleted halfedges are represantatives of a
   // face boundary or a hole inside these faces. If so, replace he3 by he1 and
   // he4 by he2.
-  if (ic1 != NULL && ic1->halfedge() == he3)
+  if (ic1 != nullptr && ic1->halfedge() == he3)
     ic1->set_halfedge (he1);
-  else if (oc1 != NULL && oc1->halfedge() == he3)
+  else if (oc1 != nullptr && oc1->halfedge() == he3)
     oc1->set_halfedge (he1);
 
-  if (ic2 != NULL && ic2->halfedge() == he4)
+  if (ic2 != nullptr && ic2->halfedge() == he4)
     ic2->set_halfedge (he2);
-  else if (oc2 != NULL && oc2->halfedge() == he4)
+  else if (oc2 != nullptr && oc2->halfedge() == he4)
     oc2->set_halfedge (he2);
 
   // If he3 is the incident halfedge to its target, replace it by he1.
@@ -625,7 +625,7 @@ compare_x (const Point_2& p, const Vertex* v) const
     Arr_curve_end v_ind = ARR_MIN_END;
     const X_monotone_curve_2* v_cv = _curve (v, v_ind);
 
-    CGAL_assertion(v_cv != NULL);
+    CGAL_assertion(v_cv != nullptr);
     return
       (this->m_geom_traits->compare_x_point_curve_end_2_object()(p, *v_cv,
                                                                  v_ind));
@@ -659,7 +659,7 @@ compare_xy (const Point_2& p, const Vertex* v) const
     Arr_curve_end v_ind = ARR_MIN_END;
     const X_monotone_curve_2* v_cv = _curve (v, v_ind);
 
-    CGAL_assertion (v_cv != NULL);
+    CGAL_assertion (v_cv != nullptr);
 
     Comparison_result res =
       this->m_geom_traits->compare_x_point_curve_end_2_object() (p, *v_cv,
@@ -724,7 +724,7 @@ _curve (const Vertex* v, Arr_curve_end& ind) const
     he = he->next()->opposite();
 
     // No incident curve were found:
-    if (he == v->halfedge()) return (NULL);
+    if (he == v->halfedge()) return (nullptr);
   }
 
   // The halfedge he is directed toward v, so if it is directed from left to
@@ -844,7 +844,7 @@ _is_on_fictitious_edge(const X_monotone_curve_2& cv, Arr_curve_end ind,
       // arrangement, but it hasn't been associated with a valid halfedge
       // yet, as the insertion process is still ongoing.
       // The comparison result in this case is trivial.
-      if (v_cv1 != NULL) {
+      if (v_cv1 != nullptr) {
         res1 =
           this->m_geom_traits->compare_x_curve_ends_2_object()(cv, ind,
                                                                *v_cv1, v_ind);
@@ -878,7 +878,7 @@ _is_on_fictitious_edge(const X_monotone_curve_2& cv, Arr_curve_end ind,
       // arrangement, but it hasn't been associated with a valid halfedge
       // yet, as the insertion process is still ongoing.
       // The comparison result in this case is trivial.
-      if (v_cv2 != NULL) {
+      if (v_cv2 != nullptr) {
         res2 =
           this->m_geom_traits->compare_x_curve_ends_2_object()(cv, ind,
                                                                *v_cv2, v_ind);

Arrangement_on_surface_2/include/CGAL/Arr_trapezoid_ric_point_location.h

@@ -148,7 +148,7 @@ public:
   Arr_trapezoid_ric_point_location (bool with_guarantees = true, 
                            double depth_thrs = CGAL_TD_DEFAULT_DEPTH_THRESHOLD, 
                            double size_thrs = CGAL_TD_DEFAULT_SIZE_THRESHOLD) 
-    : m_traits (NULL), m_with_guarantees(with_guarantees)
+    : m_traits (nullptr), m_with_guarantees(with_guarantees)
   {
     td.set_with_guarantees(with_guarantees);
     td.depth_threshold(depth_thrs);

Arrangement_on_surface_2/include/CGAL/Arr_triangulation_point_location.h

@@ -129,7 +129,7 @@ protected:
 public:
   /*! Default constructor. */
   Arr_triangulation_point_location() :
-    m_traits(NULL),
+    m_traits(nullptr),
     m_ignore_notifications(false),
     m_ignore_remove_edge(false)
   {}

Arrangement_on_surface_2/include/CGAL/Arr_unb_planar_topology_traits_2.h

@@ -342,7 +342,7 @@ public:
                                 Arr_parameter_space /* ps_y */) const
   {
     CGAL_error();
-    return (NULL);
+    return (nullptr);
   }
 
   /*! Locate a DCEL feature that contains the given unbounded curve end.
@@ -492,7 +492,7 @@ protected:
    * \param ind Output: ARR_MIN_END if the vertex is induced by the minimal end;
    *                    ARR_MAX_END if it is induced by the curve's maximal end.
    * \pre v is a valid (not fictitious) boundary.
-   * \return The curve that induces v, or NULL if v has no incident curves yet.
+   * \return The curve that induces v, or nullptr if v has no incident curves yet.
    */
   const X_monotone_curve_2* _curve(const Vertex* v, Arr_curve_end& ind) const;
 

Arrangement_on_surface_2/include/CGAL/Arr_walk_along_line_point_location.h

@@ -87,9 +87,9 @@ protected:
 public:
   /*! Default constructor. */
   Arr_walk_along_line_point_location() : 
-    p_arr(NULL),
+    p_arr(nullptr),
-    geom_traits(NULL),
+    geom_traits(nullptr),
-    top_traits(NULL)
+    top_traits(nullptr)
   {}
         
   /*! Constructor given an arrangement. */
@@ -113,9 +113,9 @@ public:
   /*! Detach from the current arrangement object. */
   void detach()
   {
-    p_arr = NULL;
+    p_arr = nullptr;
-    geom_traits = NULL;
+    geom_traits = nullptr;
-    top_traits = NULL;
+    top_traits = nullptr;
   }
  
   /*!

Arrangement_on_surface_2/include/CGAL/Arrangement_2/Arrangement_on_surface_2_global.h

@@ -110,7 +110,7 @@ void insert(Arrangement_on_surface_2<GeometryTraits_2, TopologyTraits>& arr,
     // Act according to the type of the current object.
     x_curve = object_cast<typename Gt2::X_monotone_curve_2>(&(*obj_iter));
 
-    if (x_curve != NULL) {
+    if (x_curve != nullptr) {
       // Inserting an x-monotone curve:
       // Initialize the zone-computation object with the given curve.
       arr_zone.init(*x_curve, pl);
@@ -128,7 +128,7 @@ void insert(Arrangement_on_surface_2<GeometryTraits_2, TopologyTraits>& arr,
     }
     else {
       iso_p = object_cast<typename Gt2::Point_2>(&(*obj_iter));
-      CGAL_assertion(iso_p != NULL);
+      CGAL_assertion(iso_p != nullptr);
 
       // Inserting a point into the arrangement:
       insert_point(arr, *iso_p, pl);
@@ -680,7 +680,7 @@ insert_non_intersecting_curve
   const Arr_parameter_space by1 =
     geom_traits->parameter_space_in_y_2_object()(c, ARR_MIN_END);
   CGAL::Object obj1;
-  const Vertex_const_handle* vh1 = NULL;
+  const Vertex_const_handle* vh1 = nullptr;
 
   if ((bx1 == ARR_INTERIOR) && (by1 == ARR_INTERIOR)) {
     // We have a normal left endpoint with no boundary conditions:
@@ -690,7 +690,7 @@ insert_non_intersecting_curve
     // The endpoint must not lie on an existing edge, but may coincide with
     // and existing vertex vh1.
     CGAL_precondition_msg
-      (object_cast<Halfedge_const_handle>(&obj1) == NULL,
+      (object_cast<Halfedge_const_handle>(&obj1) == nullptr,
        "The curve must not intersect an existing edge.");
 
     vh1 = object_cast<Vertex_const_handle>(&obj1);
@@ -701,7 +701,7 @@ insert_non_intersecting_curve
     obj1 = arr_access.locate_curve_end(c, ARR_MIN_END, bx1, by1);
 
     CGAL_precondition_msg
-      (object_cast<Halfedge_const_handle>(&obj1) == NULL,
+      (object_cast<Halfedge_const_handle>(&obj1) == nullptr,
        "The curve must not overlap an existing edge.");
 
     vh1 = object_cast<Vertex_const_handle>(&obj1);
@@ -714,7 +714,7 @@ insert_non_intersecting_curve
   const Arr_parameter_space  by2 =
     geom_traits->parameter_space_in_y_2_object()(c, ARR_MAX_END);
   CGAL::Object obj2;
-  const Vertex_const_handle* vh2 = NULL;
+  const Vertex_const_handle* vh2 = nullptr;
 
   if ((bx2 == ARR_INTERIOR) && (by2 == ARR_INTERIOR)) {
     // We have a normal right endpoint with no boundary conditions:
@@ -724,7 +724,7 @@ insert_non_intersecting_curve
     // The endpoint must not lie on an existing edge, but may coincide with
     // and existing vertex vh2.
     CGAL_precondition_msg
-      (object_cast<Halfedge_const_handle>(&obj2) == NULL,
+      (object_cast<Halfedge_const_handle>(&obj2) == nullptr,
        "The curve must not intersect an existing edge.");
 
     vh2 = object_cast<Vertex_const_handle>(&obj2);
@@ -739,7 +739,7 @@ insert_non_intersecting_curve
     obj2 = arr_access.locate_curve_end(c, ARR_MAX_END, bx2, by2);
 
     CGAL_precondition_msg
-      (object_cast<Halfedge_const_handle>(&obj2) == NULL,
+      (object_cast<Halfedge_const_handle>(&obj2) == nullptr,
        "The curve must not overlap an existing edge.");
 
     vh2 = object_cast<Vertex_const_handle>(&obj2);
@@ -754,8 +754,8 @@ insert_non_intersecting_curve
   // accordingly.
   typename Arr::Halfedge_handle new_he;
 
-  if (vh1 != NULL) {
+  if (vh1 != nullptr) {
-    if (vh2 != NULL) {
+    if (vh2 != nullptr) {
       // Both endpoints are associated with a existing vertices.
       // In this case insert_at_vertices() already returns a halfedge
       // directed from left to right.
@@ -772,7 +772,7 @@ insert_non_intersecting_curve
     }
   }
   else {
-    if (vh2 != NULL) {
+    if (vh2 != nullptr) {
       // Only the right endpoint is associated with an existing vertex.
       // In this case insert_from_left_vertex() returns a halfedge directed
       // to the new vertex it creates, so it is directed from right to left
@@ -797,10 +797,10 @@ insert_non_intersecting_curve
       //           << (*fh2)->number_of_outer_ccbs() << std::endl;
 
       CGAL_assertion_msg
-        ((fh1 != NULL) && (fh2 != NULL) && ((*fh1) == (*fh2)),
+        ((fh1 != nullptr) && (fh2 != nullptr) && ((*fh1) == (*fh2)),
          "The curve intersects the interior of existing edges.");
 
-      if ((fh1 != NULL) && (fh2 != NULL) && (*fh1 == *fh2)) {
+      if ((fh1 != nullptr) && (fh2 != nullptr) && (*fh1 == *fh2)) {
         new_he = arr.insert_in_face_interior(c, arr.non_const_handle (*fh1));
       }
     }
@@ -1164,13 +1164,13 @@ insert_point(Arrangement_on_surface_2<GeometryTraits_2, TopologyTraits>& arr,
 
   arr_access.notify_before_global_change();
 
-  if ((fh = object_cast<typename Arr::Face_const_handle>(&obj)) != NULL) {
+  if ((fh = object_cast<typename Arr::Face_const_handle>(&obj)) != nullptr) {
     // p lies inside a face: Insert it as an isolated vertex it the interior of
     // this face.
     vh_for_p = arr.insert_in_face_interior(p, arr.non_const_handle (*fh));
   }
   else if ((hh = object_cast<typename Arr::Halfedge_const_handle>(&obj)) !=
-           NULL)
+           nullptr)
   {
     // p lies in the interior of an edge: Split this edge to create a new
     // vertex associated with p.
@@ -1189,7 +1189,7 @@ insert_point(Arrangement_on_surface_2<GeometryTraits_2, TopologyTraits>& arr,
     // In this case p lies on an existing vertex, so we just update this
     // vertex.
     vh = object_cast<typename Arr::Vertex_const_handle>(&obj);
-    CGAL_assertion (vh != NULL);
+    CGAL_assertion (vh != nullptr);
 
     vh_for_p = arr.modify_vertex (arr.non_const_handle (*vh), p);
   }
@@ -1634,20 +1634,20 @@ do_intersect(Arrangement_on_surface_2<GeometryTraits_2, TopologyTraits>& arr,
   for (obj_iter = x_objects.begin(); obj_iter != x_objects.end(); ++obj_iter) {
     // Act according to the type of the current object.
     x_curve = object_cast<typename Gt2::X_monotone_curve_2>(&(*obj_iter));
-    if (x_curve != NULL) {
+    if (x_curve != nullptr) {
       // Check if the x-monotone subcurve intersects the arrangement.
       if (do_intersect(arr, *x_curve, pl) == true)
         return true;
     }
     else {
       iso_p = object_cast<typename Gt2::Point_2>(&(*obj_iter));
-      CGAL_assertion(iso_p != NULL);
+      CGAL_assertion(iso_p != nullptr);
 
       // Check whether the isolated point lies inside a face (otherwise,
       // it conincides with a vertex or an edge).
       CGAL::Object  obj = pl.locate (*iso_p);
 
-      return (object_cast<typename Arr::Face_const_handle>(&obj) != NULL);
+      return (object_cast<typename Arr::Face_const_handle>(&obj) != nullptr);
     }
   }
 

Arrangement_on_surface_2/include/CGAL/Arrangement_2/Arrangement_on_surface_2_impl.h

@@ -96,7 +96,7 @@ Arrangement_on_surface_2<GeomTraits, TopTraits>::Arrangement_on_surface_2() :
 template <typename GeomTraits, typename TopTraits>
 Arrangement_on_surface_2<GeomTraits, TopTraits>::
 Arrangement_on_surface_2(const Self& arr) :
-  m_geom_traits(NULL),
+  m_geom_traits(nullptr),
   m_own_traits(false)
 {
   assign(arr);
@@ -206,9 +206,9 @@ void Arrangement_on_surface_2<GeomTraits, TopTraits>::assign(const Self& arr)
   }
 
   // Take care of the traits object.
-  if (m_own_traits && (m_geom_traits != NULL)) {
+  if (m_own_traits && (m_geom_traits != nullptr)) {
     delete m_geom_traits;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
   }
 
   m_geom_traits = (arr.m_own_traits) ? new Traits_adaptor_2 : arr.m_geom_traits;
@@ -237,9 +237,9 @@ Arrangement_on_surface_2<GeomTraits, TopTraits>::~Arrangement_on_surface_2()
       _delete_curve(eit->curve());
 
   // Free the traits object, if necessary.
-  if (m_own_traits && (m_geom_traits != NULL)) {
+  if (m_own_traits && (m_geom_traits != nullptr)) {
     delete m_geom_traits;
-    m_geom_traits = NULL;
+    m_geom_traits = nullptr;
   }
 
   // Detach all observers still attached to the arrangement.
@@ -333,7 +333,7 @@ insert_in_face_interior(const X_monotone_curve_2& cv, Face_handle f)
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MIN_END);
   const Arr_parameter_space  ps_y1 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MIN_END);
-  DHalfedge* fict_prev1 = NULL;
+  DHalfedge* fict_prev1 = nullptr;
 
   DVertex* v1 = ((ps_x1 == ARR_INTERIOR) && (ps_y1 == ARR_INTERIOR)) ?
     // The curve has a valid left endpoint: Create a new vertex associated
@@ -349,7 +349,7 @@ insert_in_face_interior(const X_monotone_curve_2& cv, Face_handle f)
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MAX_END);
   const Arr_parameter_space  ps_y2 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MAX_END);
-  DHalfedge* fict_prev2 = NULL;
+  DHalfedge* fict_prev2 = nullptr;
 
   DVertex* v2 = ((ps_x2 == ARR_INTERIOR) && (ps_y2 == ARR_INTERIOR)) ?
     // The curve has a valid right endpoint: Create a new vertex associated
@@ -363,15 +363,15 @@ insert_in_face_interior(const X_monotone_curve_2& cv, Face_handle f)
   // lexicographically smaller than v2).
   DHalfedge* new_he;
 
-  if ((fict_prev1 == NULL) && (fict_prev2 == NULL))
+  if ((fict_prev1 == nullptr) && (fict_prev2 == nullptr))
     // Both vertices represent valid points.
     new_he = _insert_in_face_interior(p_f, cv, ARR_LEFT_TO_RIGHT, v1, v2);
-  else if ((fict_prev1 == NULL) && (fict_prev2 != NULL)) {
+  else if ((fict_prev1 == nullptr) && (fict_prev2 != nullptr)) {
     // v1 represents a valid point and v2 is inserted using its predecessor.
     new_he = _insert_from_vertex(fict_prev2, cv, ARR_RIGHT_TO_LEFT, v1);
     new_he = new_he->opposite();
   }
-  else if ((fict_prev1 != NULL) && (fict_prev2 == NULL))
+  else if ((fict_prev1 != nullptr) && (fict_prev2 == nullptr))
     // v1 is inserted using its predecessor and v2 represents a valid point.
     new_he = _insert_from_vertex(fict_prev1, cv, ARR_LEFT_TO_RIGHT, v2);
   else {
@@ -455,8 +455,8 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MAX_END);
   const Arr_parameter_space  ps_y2 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MAX_END);
-  DVertex* v2 = NULL;
+  DVertex* v2 = nullptr;
-  DHalfedge* fict_prev2 = NULL;
+  DHalfedge* fict_prev2 = nullptr;
 
   if ((ps_x2 == ARR_INTERIOR) && (ps_y2 == ARR_INTERIOR))
     // The curve has a valid right endpoint: Create a new vertex associated
@@ -469,8 +469,8 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
     // The given vertex is an isolated one: We should in fact insert the curve
     // in the interior of the face containing this vertex.
     DVertex* v1 = _vertex(v);
-    DIso_vertex* iv = NULL;
+    DIso_vertex* iv = nullptr;
-    DFace* p_f = NULL;
+    DFace* p_f = nullptr;
 
     if (v->is_isolated()) {
       // Obtain the face from the isolated vertex.
@@ -485,13 +485,13 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
 
     // If the vertex that corresponds to cv's right end has boundary
     // conditions, create it now.
-    if (v2 == NULL)
+    if (v2 == nullptr)
       // Locate the DCEL features that will be used for inserting the curve's
       // right end.
       v2 = _place_and_set_curve_end(p_f, cv, ARR_MAX_END, ps_x2, ps_y2,
                                     &fict_prev2);
 
-    if (iv != NULL) {
+    if (iv != nullptr) {
       // Remove the isolated vertex v1, as it will not be isolated any more.
       p_f->erase_isolated_vertex(iv);
       _dcel().delete_isolated_vertex(iv);
@@ -500,7 +500,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
     // Create the edge connecting the two vertices (note that we know that
     // v1 is smaller than v2).
     DHalfedge* new_he;
-    if (fict_prev2 == NULL)
+    if (fict_prev2 == nullptr)
       new_he = _insert_in_face_interior(p_f, cv, ARR_LEFT_TO_RIGHT, v1, v2);
     else {
       new_he = _insert_from_vertex(fict_prev2, cv, ARR_RIGHT_TO_LEFT, v1);
@@ -516,7 +516,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
   // which the new curve should be inserted.
   DHalfedge* prev1 = _locate_around_vertex(_vertex(v), cv, ARR_MIN_END);
   CGAL_assertion_msg
-    (prev1 != NULL,
+    (prev1 != nullptr,
      "The inserted curve cannot be located in the arrangement.");
 
   DFace* f1 = prev1->is_on_inner_ccb() ? prev1->inner_ccb()->face() :
@@ -524,7 +524,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
 
   // If the vertex that corresponds to cv's right end has boundary conditions,
   // create it now.
-  if (v2 == NULL)
+  if (v2 == nullptr)
     // Locate the DCEL features that will be used for inserting the curve's
     // right end.
     v2 =
@@ -534,7 +534,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv,
   // than v2).
   DHalfedge* new_he;
 
-  if (fict_prev2 == NULL)
+  if (fict_prev2 == nullptr)
     // Insert the halfedge given the predecessor halfedge of v1.
     new_he = _insert_from_vertex(prev1, cv, ARR_LEFT_TO_RIGHT, v2);
   else {
@@ -617,7 +617,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv, Halfedge_handle prev)
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MAX_END);
   const Arr_parameter_space  ps_y2 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MAX_END);
-  DHalfedge* fict_prev2 = NULL;
+  DHalfedge* fict_prev2 = nullptr;
 
   DVertex* v2 = ((ps_x2 == ARR_INTERIOR) && (ps_y2 == ARR_INTERIOR)) ?
     // The curve has a valid right endpoint: Create a new vertex associated
@@ -631,7 +631,7 @@ insert_from_left_vertex(const X_monotone_curve_2& cv, Halfedge_handle prev)
   // than v2).
   DHalfedge* new_he;
 
-  if (fict_prev2 == NULL)
+  if (fict_prev2 == nullptr)
     // Insert the halfedge given the predecessor halfedge of the left vertex.
     new_he = _insert_from_vertex(prev1, cv, ARR_LEFT_TO_RIGHT, v2);
   else {
@@ -693,8 +693,8 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MIN_END);
   const Arr_parameter_space  ps_y1 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MIN_END);
-  DVertex* v1 = NULL;
+  DVertex* v1 = nullptr;
-  DHalfedge* fict_prev1 = NULL;
+  DHalfedge* fict_prev1 = nullptr;
 
   if ((ps_x1 == ARR_INTERIOR) && (ps_y1 == ARR_INTERIOR))
     // The curve has a valid left endpoint: Create a new vertex associated
@@ -707,8 +707,8 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
     // The given vertex is an isolated one: We should in fact insert the curve
     // in the interior of the face containing this vertex.
     DVertex* v2 = _vertex(v);
-    DIso_vertex* iv = NULL;
+    DIso_vertex* iv = nullptr;
-    DFace* p_f = NULL;
+    DFace* p_f = nullptr;
 
     if (v->is_isolated()) {
       // Obtain the face from the isolated vertex.
@@ -723,13 +723,13 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
 
     // If the vertex that corresponds to cv's left end has boundary
     // conditions, create it now.
-    if (v1 == NULL)
+    if (v1 == nullptr)
       // Locate the DCEL features that will be used for inserting the curve's
       // left end.
       v1 = _place_and_set_curve_end(p_f, cv, ARR_MIN_END, ps_x1, ps_y1,
                                     &fict_prev1);
 
-    if (iv != NULL) {
+    if (iv != nullptr) {
       // Remove the isolated vertex v2, as it will not be isolated any more.
       p_f->erase_isolated_vertex(iv);
       _dcel().delete_isolated_vertex(iv);
@@ -737,7 +737,7 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
 
     // Create the edge connecting the two vertices (note that we know that
     // v1 is smaller than v2).
-    DHalfedge* new_he = (fict_prev1 == NULL) ?
+    DHalfedge* new_he = (fict_prev1 == nullptr) ?
       _insert_in_face_interior(p_f, cv, ARR_LEFT_TO_RIGHT, v1, v2) :
       _insert_from_vertex(fict_prev1, cv, ARR_LEFT_TO_RIGHT, v2);
 
@@ -750,14 +750,14 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
   // which the new curve should be inserted.
   DHalfedge* prev2 = _locate_around_vertex(_vertex(v), cv, ARR_MAX_END);
   CGAL_assertion_msg
-    (prev2 != NULL, "The inserted curve cannot be located in the arrangement.");
+    (prev2 != nullptr, "The inserted curve cannot be located in the arrangement.");
 
   DFace* f2 = prev2->is_on_inner_ccb() ? prev2->inner_ccb()->face() :
     prev2->outer_ccb()->face();
 
   // If the vertex that corresponds to cv's left end has boundary conditions,
   // create it now.
-  if (v1 == NULL)
+  if (v1 == nullptr)
     // Locate the DCEL features that will be used for inserting the curve's
     // left end.
     v1 =
@@ -767,7 +767,7 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
   // than v1).
   DHalfedge* new_he;
 
-  if (fict_prev1 == NULL)
+  if (fict_prev1 == nullptr)
     // Insert the halfedge given the predecessor halfedge of v2.
     new_he = _insert_from_vertex(prev2, cv, ARR_RIGHT_TO_LEFT, v1);
   else {
@@ -852,7 +852,7 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
     m_geom_traits->parameter_space_in_x_2_object()(cv, ARR_MIN_END);
   const Arr_parameter_space  ps_y1 =
     m_geom_traits->parameter_space_in_y_2_object()(cv, ARR_MIN_END);
-  DHalfedge* fict_prev1 = NULL;
+  DHalfedge* fict_prev1 = nullptr;
 
   DVertex* v1 = ((ps_x1 == ARR_INTERIOR) && (ps_y1 == ARR_INTERIOR)) ?
     // The curve has a valid left endpoint: Create a new vertex associated
@@ -866,7 +866,7 @@ insert_from_right_vertex(const X_monotone_curve_2& cv,
   // than v1).
   DHalfedge* new_he;
 
-  if (fict_prev1 == NULL)
+  if (fict_prev1 == nullptr)
     // Insert the halfedge given the predecessor halfedge of the right vertex.
     new_he = _insert_from_vertex(prev2, cv, ARR_RIGHT_TO_LEFT, v1);
   else {
@@ -1023,8 +1023,8 @@ insert_at_vertices(const X_monotone_curve_2& cv,
   if (v1->degree() == 0) {
     // Get the face containing the isolated vertex v1.
     DVertex* p_v1 = _vertex(v1);
-    DIso_vertex* iv1 = NULL;
+    DIso_vertex* iv1 = nullptr;
-    DFace* f1 = NULL;
+    DFace* f1 = nullptr;
 
     if (p_v1->is_isolated()) {
       // Obtain the containing face from the isolated vertex record.
@@ -1041,8 +1041,8 @@ insert_at_vertices(const X_monotone_curve_2& cv,
       // Both end-vertices are isolated. Make sure they are contained inside
       // the same face.
       DVertex* p_v2 = _vertex(v2);
-      DIso_vertex* iv2 = NULL;
+      DIso_vertex* iv2 = nullptr;
-      DFace* f2 = NULL;
+      DFace* f2 = nullptr;
 
       if (p_v2->is_isolated()) {
         // Obtain the containing face from the isolated vertex record.
@@ -1050,14 +1050,14 @@ insert_at_vertices(const X_monotone_curve_2& cv,
         f2 = iv2->face();
 
         CGAL_assertion_msg
-          ((f1 == NULL) || (f1 == f2),
+          ((f1 == nullptr) || (f1 == f2),
            "The two isolated vertices must be located inside the same face.");
 
         // Remove the isolated vertex v2, as it will not be isolated any more.
         f2->erase_isolated_vertex(iv2);
         _dcel().delete_isolated_vertex(iv2);
       }
-      else if (f1 == NULL)
+      else if (f1 == nullptr)
         // In this case the containing face must be given by the user.
         CGAL_precondition(f != Face_handle());
 
@@ -1073,7 +1073,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
     // which the new curve should be inserted.
     DHalfedge* prev2 = _locate_around_vertex(_vertex(v2), cv, ind2);
     CGAL_assertion_msg
-      (prev2 != NULL,
+      (prev2 != nullptr,
        "The inserted curve cannot be located in the arrangement.");
 
     CGAL_assertion_code
@@ -1081,7 +1081,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
        prev2->outer_ccb()->face());
 
     CGAL_assertion_msg
-      ((f1 == NULL) || (f1 == f2),
+      ((f1 == nullptr) || (f1 == f2),
        "The inserted curve should not intersect the existing arrangement.");
 
     // Perform the insertion. Note that the returned halfedge is directed
@@ -1095,8 +1095,8 @@ insert_at_vertices(const X_monotone_curve_2& cv,
   else if (v2->degree() == 0) {
     // Get the face containing the isolated vertex v2.
     DVertex* p_v2 = _vertex(v2);
-    DIso_vertex* iv2 = NULL;
+    DIso_vertex* iv2 = nullptr;
-    DFace* f2 = NULL;
+    DFace* f2 = nullptr;
 
     if (v2->is_isolated()) {
       // Obtain the containing face from the isolated vertex record.
@@ -1112,7 +1112,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
     // which the new curve should be inserted.
     DHalfedge* prev1 = _locate_around_vertex(_vertex(v1), cv, ind1);
     CGAL_assertion_msg
-      (prev1 != NULL,
+      (prev1 != nullptr,
        "The inserted curve cannot be located in the arrangement.");
 
     CGAL_assertion_code
@@ -1120,7 +1120,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
        prev1->outer_ccb()->face());
 
     CGAL_assertion_msg
-      ((f2 == NULL) || (f2 == f1),
+      ((f2 == nullptr) || (f2 == f1),
        "The inserted curve should not intersect the existing arrangement.");
 
     // Perform the insertion.
@@ -1137,7 +1137,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
   DHalfedge* prev2 = _locate_around_vertex(_vertex(v2), cv, ind2);
 
   CGAL_assertion_msg
-    (((prev1 != NULL) && (prev2 != NULL)),
+    (((prev1 != nullptr) && (prev2 != nullptr)),
      "The inserted curve cannot be located in the arrangement.");
 
   // Perform the insertion.
@@ -1259,8 +1259,8 @@ insert_at_vertices(const X_monotone_curve_2& cv,
   if (v2->degree() == 0) {
     // Get the face containing the isolated vertex v2.
     DVertex* p_v2 = _vertex(v2);
-    DIso_vertex* iv2 = NULL;
+    DIso_vertex* iv2 = nullptr;
-    DFace* f2 = NULL;
+    DFace* f2 = nullptr;
 
     if (v2->is_isolated()) {
       iv2 = p_v2->isolated_vertex();
@@ -1287,7 +1287,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
   // which the new curve should be inserted.
   DHalfedge* prev2 = _locate_around_vertex(_vertex(v2), cv, ind2);
   CGAL_assertion_msg
-    (prev2 != NULL, "The inserted curve cannot be located in the arrangement.");
+    (prev2 != nullptr, "The inserted curve cannot be located in the arrangement.");
 
   // Perform the insertion.
   return (insert_at_vertices(cv, prev1, Halfedge_handle(prev2)));
@@ -1652,10 +1652,10 @@ merge_edge(Halfedge_handle e1, Halfedge_handle e2,
   //
   DHalfedge* _e1 = _halfedge(e1);
   DHalfedge* _e2 = _halfedge(e2);
-  DHalfedge* he1 = NULL;
+  DHalfedge* he1 = nullptr;
-  DHalfedge* he2 = NULL;
+  DHalfedge* he2 = nullptr;
-  DHalfedge* he3 = NULL;
+  DHalfedge* he3 = nullptr;
-  DHalfedge* he4 = NULL;
+  DHalfedge* he4 = nullptr;
 
   if (_e1->vertex() == _e2->opposite()->vertex()) {
     he1 = _e1;
@@ -1709,11 +1709,11 @@ merge_edge(Halfedge_handle e1, Halfedge_handle e2,
 
   // Keep pointers to the components that contain two halfedges he3 and he2,
   // pointing at the end vertices of the merged halfedge.
-  DInner_ccb* ic1 = (he3->is_on_inner_ccb()) ? he3->inner_ccb() : NULL;
+  DInner_ccb* ic1 = (he3->is_on_inner_ccb()) ? he3->inner_ccb() : nullptr;
-  DOuter_ccb* oc1 = (ic1 == NULL) ? he3->outer_ccb() : NULL;
+  DOuter_ccb* oc1 = (ic1 == nullptr) ? he3->outer_ccb() : nullptr;
 
-  DInner_ccb* ic2 = (he4->is_on_inner_ccb()) ? he4->inner_ccb() : NULL;
+  DInner_ccb* ic2 = (he4->is_on_inner_ccb()) ? he4->inner_ccb() : nullptr;
-  DOuter_ccb* oc2 = (ic2 == NULL) ? he4->outer_ccb() : NULL;
+  DOuter_ccb* oc2 = (ic2 == nullptr) ? he4->outer_ccb() : nullptr;
 
   // Notify the observers that we are about to merge an edge.
   _notify_before_merge_edge(e1, e2, cv);
@@ -1723,14 +1723,14 @@ merge_edge(Halfedge_handle e1, Halfedge_handle e2,
   // the CCBs they belong to. If so, replace he3 by he1 and he4 by he2. Note
   // that as we just change the component representatives, we do not have to
   // notify the observers on the change.
-  if (oc1 != NULL && oc1->halfedge() == he3)
+  if (oc1 != nullptr && oc1->halfedge() == he3)
     oc1->set_halfedge(he1);
-  else if (ic1 != NULL && ic1->halfedge() == he3)
+  else if (ic1 != nullptr && ic1->halfedge() == he3)
     ic1->set_halfedge(he1);
 
-  if (oc2 != NULL && oc2->halfedge() == he4)
+  if (oc2 != nullptr && oc2->halfedge() == he4)
     oc2->set_halfedge(he2);
-  else if (ic2 != NULL && ic2->halfedge() == he4)
+  else if (ic2 != nullptr && ic2->halfedge() == he4)
     ic2->set_halfedge(he2);
 
   // If he3 is the incident halfedge to its target, replace it by he1.
@@ -1832,7 +1832,7 @@ _locate_around_vertex(DVertex* v,
   DHalfedge* first = v->halfedge();
   DHalfedge* curr = first;
 
-  if (curr == NULL) return NULL;
+  if (curr == nullptr) return nullptr;
 
   DHalfedge* next = curr->next()->opposite();
 
@@ -1854,7 +1854,7 @@ _locate_around_vertex(DVertex* v,
   {
     // If cv equals one of the curves associated with the halfedges, it is
     // an illegal input curve, as it already exists in the arrangement.
-    if (eq_curr || eq_next) return NULL;
+    if (eq_curr || eq_next) return nullptr;
 
     // Move to the next pair of incident halfedges.
     curr = next;
@@ -1862,7 +1862,7 @@ _locate_around_vertex(DVertex* v,
 
     // If we completed a full traversal around v without locating the
     // place for cv, it follows that cv overlaps and existing curve.
-    if (curr == first) return NULL;
+    if (curr == first) return nullptr;
   }
 
   // Return the halfedge we have located.
@@ -2173,7 +2173,7 @@ _create_boundary_vertex(const X_monotone_curve_2& cv, Arr_curve_end ind,
   if (is_open(ps_x, ps_y))
     // The curve-end lies on open boundary so the vertex is not associated
     // with a valid point.
-    v->set_point(NULL);
+    v->set_point(nullptr);
   else {
     // Create a boundary vertex associated with a valid point.
     Point_2* p_p = (ind == ARR_MIN_END) ?
@@ -2244,7 +2244,7 @@ _place_and_set_curve_end(DFace* f,
     m_topol_traits.notify_on_boundary_vertex_creation(v, cv, ind, ps_x, ps_y);
 
     // There are no edges incident to v, therefore no predecessor halfedge.
-    *p_pred = NULL;
+    *p_pred = nullptr;
   }
 
   // Return the vertex that represents the curve end.
@@ -2353,8 +2353,8 @@ _insert_from_vertex(DHalfedge* he_to, const X_monotone_curve_2& cv,
 
   // Get the incident face of the previous halfedge. Note that this will also
   // be the incident face of the two new halfedges we are about to create.
-  DInner_ccb* ic = (he_to->is_on_inner_ccb()) ? he_to->inner_ccb() : NULL;
+  DInner_ccb* ic = (he_to->is_on_inner_ccb()) ? he_to->inner_ccb() : nullptr;
-  DOuter_ccb* oc = (ic == NULL) ? he_to->outer_ccb() : NULL;
+  DOuter_ccb* oc = (ic == nullptr) ? he_to->outer_ccb() : nullptr;
 
   // The first vertex is the one that the he_to halfedge points to.
   // The second vertex is given by v.
@@ -2376,7 +2376,7 @@ _insert_from_vertex(DHalfedge* he_to, const X_monotone_curve_2& cv,
   he2->set_vertex(v2);
 
   // Set the component for the new halfedge pair.
-  if (oc != NULL) {
+  if (oc != nullptr) {
     // On an outer component:
     he1->set_outer_ccb(oc);
     he2->set_outer_ccb(oc);
@@ -2459,8 +2459,8 @@ _insert_at_vertices(DHalfedge* he_to,
                              he_away->outer_ccb()->face()) << std::endl;
 #endif
 
-  CGAL_precondition(he_to != NULL);
+  CGAL_precondition(he_to != nullptr);
-  CGAL_precondition(he_away != NULL);
+  CGAL_precondition(he_away != nullptr);
 
   // TODO EBEB 2012-10-21 rewrite the code in terms of he_to and he_away instead of prev1 and prev2
   // the remainder of the function we deal with this situation adds he1 and
@@ -2471,8 +2471,8 @@ _insert_at_vertices(DHalfedge* he_to,
   DHalfedge* prev1 = he_to;
   DHalfedge* prev2 = he_away->prev();
 
-  CGAL_precondition(prev1 != NULL);
+  CGAL_precondition(prev1 != nullptr);
-  CGAL_precondition(prev2 != NULL);
+  CGAL_precondition(prev2 != nullptr);
   CGAL_precondition(prev1 != prev2);
 
   // in general we do not swap ...
@@ -2491,10 +2491,10 @@ _insert_at_vertices(DHalfedge* he_to,
 
     // Comment EBEB 2012-08-05 hole1/hole2 appear later as ic1/ic2, but we keep
     // them here, as the usage is rather local to decide swapping
-    DInner_ccb* hole1 = (prev1->is_on_inner_ccb()) ? prev1->inner_ccb() : NULL;
+    DInner_ccb* hole1 = (prev1->is_on_inner_ccb()) ? prev1->inner_ccb() : nullptr;
-    DInner_ccb* hole2 = (prev2->is_on_inner_ccb()) ? prev2->inner_ccb() : NULL;
+    DInner_ccb* hole2 = (prev2->is_on_inner_ccb()) ? prev2->inner_ccb() : nullptr;
 
-    if ((hole1 == hole2) && (hole1 != NULL)) {
+    if ((hole1 == hole2) && (hole1 != nullptr)) {
       // .. only in this special case, we have to check whether swapping should
       // take place
 
@@ -2605,13 +2605,13 @@ _insert_at_vertices(DHalfedge* he_to,
 
   // Get the components containing the two previous halfedges and the incident
   // face (which should be the same for the two components).
-  DInner_ccb* ic1 = (prev1->is_on_inner_ccb()) ? prev1->inner_ccb() : NULL;
+  DInner_ccb* ic1 = (prev1->is_on_inner_ccb()) ? prev1->inner_ccb() : nullptr;
-  DOuter_ccb* oc1 = (ic1 == NULL) ? prev1->outer_ccb() : NULL;
+  DOuter_ccb* oc1 = (ic1 == nullptr) ? prev1->outer_ccb() : nullptr;
-  DFace* f = (ic1 != NULL) ? ic1->face() : oc1->face();
+  DFace* f = (ic1 != nullptr) ? ic1->face() : oc1->face();
-  DInner_ccb* ic2 = (prev2->is_on_inner_ccb()) ? prev2->inner_ccb() : NULL;
+  DInner_ccb* ic2 = (prev2->is_on_inner_ccb()) ? prev2->inner_ccb() : nullptr;
-  DOuter_ccb* oc2 = (ic2 == NULL) ? prev2->outer_ccb() : NULL;
+  DOuter_ccb* oc2 = (ic2 == nullptr) ? prev2->outer_ccb() : nullptr;
 
-  CGAL_precondition_code(DFace* f2 = (ic2 != NULL) ? ic2->face() : oc2->face());
+  CGAL_precondition_code(DFace* f2 = (ic2 != nullptr) ? ic2->face() : oc2->face());
 
 #if CGAL_ARRANGEMENT_ON_SURFACE_INSERT_VERBOSE
   std::cout << "ic1: " << ic1 << std::endl;
@@ -2672,7 +2672,7 @@ _insert_at_vertices(DHalfedge* he_to,
   bool split_new_face = true;
   bool is_split_face_contained = false;
 
-  if ((ic1 != NULL) && (ic1 == ic2)) {
+  if ((ic1 != nullptr) && (ic1 == ic2)) {
 
     // EBEB 2012-08-06:
     // This is new code. It relies on the (computed) signs and replaces to
@@ -2722,7 +2722,7 @@ _insert_at_vertices(DHalfedge* he_to,
 
   // Check the various cases of insertion (in the design document: the
   // various sub-cases of case 3 in the insertion procedure).
-  if (((ic1 != NULL) || (ic2 != NULL)) && (ic1 != ic2)) {
+  if (((ic1 != nullptr) || (ic2 != nullptr)) && (ic1 != ic2)) {
     // In case we have to connect two disconnected components, no new face
     // is created.
     new_face = false;
@@ -2732,7 +2732,7 @@ _insert_at_vertices(DHalfedge* he_to,
     // of the face.
     Face_handle fh(f);
 
-    if ((ic1 != NULL) && (ic2 != NULL)) {
+    if ((ic1 != nullptr) && (ic2 != nullptr)) {
       // In this case (3.1) we have to connect to inner CCBs (holes) inside f.
       // Notify the observers that we are about to merge two holes in the face.
       _notify_before_merge_inner_ccb(fh,
@@ -2769,7 +2769,7 @@ _insert_at_vertices(DHalfedge* he_to,
       DHalfedge* ccb_first;
       DHalfedge* ccb_last;
 
-      if (ic1 != NULL) {
+      if (ic1 != nullptr) {
         // We remove the inner CCB ic1 and merge in with the outer CCB oc2.
         del_ic = ic1;
         oc = oc2;
@@ -2809,7 +2809,7 @@ _insert_at_vertices(DHalfedge* he_to,
   }
   else if (! split_new_face) {
     // RWRW: NEW!
-    CGAL_assertion((ic1 == ic2) && (ic1 != NULL));
+    CGAL_assertion((ic1 == ic2) && (ic1 != nullptr));
 
     // Handle the special case where we close an inner CCB, such that
     // we form two outer CCBs of the same face.
@@ -2920,7 +2920,7 @@ _insert_at_vertices(DHalfedge* he_to,
     // or on the same outer CCB (distinguish case 3.3 and case 3.4).
     bool   is_hole;
 
-    if (ic1 != NULL) {
+    if (ic1 != nullptr) {
       // In this case (3.3) we have two distinguish two sub-cases.
       if (is_split_face_contained) {
         // Comment: This is true for all non-identification topologies
@@ -3079,7 +3079,7 @@ _insert_at_vertices(DHalfedge* he_to,
     _notify_after_split_face(fh, Face_handle(new_f), is_hole);
   }
   else {
-    CGAL_assertion((oc1 != NULL) && (oc2 != NULL) && (oc1 != oc2));
+    CGAL_assertion((oc1 != nullptr) && (oc2 != nullptr) && (oc1 != oc2));
 
     // In case prev1 and prev2 belong to different outer CCBs of the same
     // face f (case 3.5), we have to merge this ccbs into one. Note that we
@@ -3122,12 +3122,12 @@ _insert_at_vertices(DHalfedge* he_to,
 #if 0
   {
     DHalfedge* he1 = he2->opposite();
-    DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : NULL;
+    DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : nullptr;
-    DOuter_ccb* oc1 = (ic1 == NULL) ? he1->outer_ccb() : NULL;
+    DOuter_ccb* oc1 = (ic1 == nullptr) ? he1->outer_ccb() : nullptr;
-    DFace* f1 = (ic1 != NULL) ? ic1->face() : oc1->face();
+    DFace* f1 = (ic1 != nullptr) ? ic1->face() : oc1->face();
-    DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : NULL;
+    DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : nullptr;
-    DOuter_ccb* oc2 = (ic2 == NULL) ? he2->outer_ccb() : NULL;
+    DOuter_ccb* oc2 = (ic2 == nullptr) ? he2->outer_ccb() : nullptr;
-    DFace* f2 = (ic2 != NULL) ? ic2->face() : oc2->face();
+    DFace* f2 = (ic2 != nullptr) ? ic2->face() : oc2->face();
     CGAL_postcondition((ic1 != ic2) || (f1 == f2));
   }
 #endif
@@ -3337,10 +3337,10 @@ _split_edge(DHalfedge* e, DVertex* v,
   // Get the split halfedge and its twin, its source and target.
   DHalfedge* he1 = e;
   DHalfedge* he2 = he1->opposite();
-  DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : NULL;
+  DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : nullptr;
-  DOuter_ccb* oc1 = (ic1 == NULL) ? he1->outer_ccb() : NULL;
+  DOuter_ccb* oc1 = (ic1 == nullptr) ? he1->outer_ccb() : nullptr;
-  DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : NULL;
+  DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : nullptr;
-  DOuter_ccb* oc2 = (ic2 == NULL) ? he2->outer_ccb() : NULL;
+  DOuter_ccb* oc2 = (ic2 == nullptr) ? he2->outer_ccb() : nullptr;
 
   // Notify the observers that we are about to split an edge.
   _notify_before_split_edge(Halfedge_handle(e), Vertex_handle(v), cv1, cv2);
@@ -3370,7 +3370,7 @@ _split_edge(DHalfedge* e, DVertex* v,
     // he1 and he2 form an "antenna", so he4 becomes he3's successor.
     he3->set_next(he4);
 
-  if (oc1 != NULL)
+  if (oc1 != nullptr)
     he3->set_outer_ccb(oc1);
   else
     he3->set_inner_ccb(ic1);
@@ -3379,7 +3379,7 @@ _split_edge(DHalfedge* e, DVertex* v,
   he4->set_vertex(v);
   he4->set_next(he2);
 
-  if (oc2 != NULL)
+  if (oc2 != nullptr)
     he4->set_outer_ccb(oc2);
   else
     he4->set_inner_ccb(ic2);
@@ -3472,8 +3472,8 @@ _compute_indices(Arr_parameter_space ps_x_curr, Arr_parameter_space ps_y_curr,
 // Precondition The OutputIterator must be a back inserter.
 // Precondition The traveresed ccb is an inner ccb; thus, it cannot be
 //              on an open boundary.
-// Postcondition If NULL is a local minimum, it is inserted first.
+// Postcondition If nullptr is a local minimum, it is inserted first.
-//                No other local minima can be NULL.
+//                No other local minima can be nullptr.
 template <typename GeomTraits, typename TopTraits>
 template <typename OutputIterator>
 std::pair<Sign, Sign>
@@ -3553,7 +3553,7 @@ _compute_signs_and_local_minima(const DHalfedge* he_to,
 
   if ((cv_dir == ARR_RIGHT_TO_LEFT) &&
       (he_away->direction() == ARR_LEFT_TO_RIGHT)) {
-    const DHalfedge* null_he = NULL;
+    const DHalfedge* null_he = nullptr;
     *local_mins_it++ = std::make_pair(null_he, x_index);
   }
 
@@ -3712,7 +3712,7 @@ _compute_signs_and_min(const DHalfedge* he_anchor,
                        int& index_min) const
 {
   // Initialize
-  const DHalfedge* he_min = NULL;
+  const DHalfedge* he_min = nullptr;
   ps_x_min = ARR_INTERIOR;
   ps_y_min = ARR_INTERIOR;
   index_min = 0;
@@ -3795,7 +3795,7 @@ _compute_signs_and_min(const DHalfedge* he_anchor,
       // Test the halfedge incident to the leftmost vertex.
       // Note that we may visit the same vertex several times.
 
-      if ((he_min == NULL) ||
+      if ((he_min == nullptr) ||
           (index_curr < index_min) ||
           ((index_curr == index_min) &&
            ((he_curr->vertex() != he_min->vertex()) &&
@@ -4023,9 +4023,9 @@ _defines_outer_ccb_of_new_face(const DHalfedge* he_to,
   int index_min = lm_it->second;
   const DHalfedge* he_min = lm_it->first;
   const DVertex* v_min =
-    (he_min == NULL) ? he_away->opposite()->vertex() : he_min->vertex();
+    (he_min == nullptr) ? he_away->opposite()->vertex() : he_min->vertex();
   const X_monotone_curve_2* cv_min =
-    (he_min == NULL) ? &cv : &(he_min->curve());
+    (he_min == nullptr) ? &cv : &(he_min->curve());
   Arr_parameter_space ps_x_min = parameter_space_in_x(*cv_min, ARR_MIN_END);
   Arr_parameter_space ps_y_min = parameter_space_in_y(*cv_min, ARR_MIN_END);
 
@@ -4077,7 +4077,7 @@ _defines_outer_ccb_of_new_face(const DHalfedge* he_to,
     }
   }
 
-  CGAL_assertion(v_min != NULL);
+  CGAL_assertion(v_min != nullptr);
   CGAL_assertion(!v_min->has_null_point());
 
 #if CGAL_ARRANGEMENT_ON_SURFACE_INSERT_VERBOSE
@@ -4086,7 +4086,7 @@ _defines_outer_ccb_of_new_face(const DHalfedge* he_to,
   if (he_min)
     std::cout << he_min->opposite()->vertex()->point()
               << " => " << he_min->vertex()->point();
-  else std::cout << "NULL";
+  else std::cout << "nullptr";
   std::cout << std::endl;
 #endif
 
@@ -4096,7 +4096,7 @@ _defines_outer_ccb_of_new_face(const DHalfedge* he_to,
   // to the right of the leftmost vertex. We compare them to the right of this
   // point to determine whether he_to (the curve) and he_away are incident to
   // the hole to be created or not.
-  const X_monotone_curve_2& cv_next = (he_min == NULL) ?
+  const X_monotone_curve_2& cv_next = (he_min == nullptr) ?
     he_away->curve() : ((he_min == he_to) ? cv : he_min->next()->curve());
   return _is_above(*cv_min, cv_next, v_min->point(), ps_y_min,
                    Top_or_bottom_sides_category());
@@ -4202,12 +4202,12 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
   // belong to and their incident faces.
   DHalfedge* he1 = e;
   DHalfedge* he2 = e->opposite();
-  DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : NULL;
+  DInner_ccb* ic1 = (he1->is_on_inner_ccb()) ? he1->inner_ccb() : nullptr;
-  DOuter_ccb* oc1 = (ic1 == NULL) ? he1->outer_ccb() : NULL;
+  DOuter_ccb* oc1 = (ic1 == nullptr) ? he1->outer_ccb() : nullptr;
-  DFace* f1 = (oc1 != NULL) ? oc1->face() : ic1->face();
+  DFace* f1 = (oc1 != nullptr) ? oc1->face() : ic1->face();
-  DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : NULL;
+  DInner_ccb* ic2 = (he2->is_on_inner_ccb()) ? he2->inner_ccb() : nullptr;
-  DOuter_ccb* oc2 = (ic2 == NULL) ? he2->outer_ccb() : NULL;
+  DOuter_ccb* oc2 = (ic2 == nullptr) ? he2->outer_ccb() : nullptr;
-  DFace* f2 = (oc2 != NULL) ? oc2->face() : ic2->face();
+  DFace* f2 = (oc2 != nullptr) ? oc2->face() : ic2->face();
 
 #if CGAL_ARRANGEMENT_ON_SURFACE_INSERT_VERBOSE
 #if 0
@@ -4419,8 +4419,8 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
 #endif
 
   // Now the real removal starts.
-  DHalfedge* prev1 = NULL;
+  DHalfedge* prev1 = nullptr;
-  DHalfedge* prev2 = NULL;
+  DHalfedge* prev2 = nullptr;
 
   // Notify the observers that we are about to remove an edge.
   Halfedge_handle  hh(e);
@@ -4432,7 +4432,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
   if (f1 == f2) {
     // Check whether the two halfedges are successors along the face boundary.
     if ((he1->next() == he2) && (he2->next() == he1)) {
-      CGAL_assertion((ic1 != NULL) && (ic1 == ic2));
+      CGAL_assertion((ic1 != nullptr) && (ic1 == ic2));
 
       // The two halfedges form a "singleton" hole inside the incident face
       // (case 1 of the removal procedure, as detailed in the design document),
@@ -4463,7 +4463,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
         if ((v1->parameter_space_in_x() != ARR_INTERIOR) ||
             (v1->parameter_space_in_y() != ARR_INTERIOR))
         {
-          v1->set_halfedge(NULL);    // disconnect the end vertex
+          v1->set_halfedge(nullptr);    // disconnect the end vertex
           _remove_vertex_if_redundant(v1, f1);
         }
         else {
@@ -4485,7 +4485,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
         if ((v2->parameter_space_in_x() != ARR_INTERIOR) ||
             (v2->parameter_space_in_y() != ARR_INTERIOR))
         {
-          v2->set_halfedge(NULL);    // disconnect the end vertex
+          v2->set_halfedge(nullptr);    // disconnect the end vertex
           _remove_vertex_if_redundant(v2, f1);
         }
         else {
@@ -4533,10 +4533,10 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
       // In case the halfedges to be deleted are represantatives of their
       // CCB (note that noth should belong to the same CCB, be it an outer
       // CCB or an inner one), make prev1 the components representative.
-      if ((oc1 != NULL) &&
+      if ((oc1 != nullptr) &&
           ((oc1->halfedge() == he1) || (oc1->halfedge() == he2)))
         oc1->set_halfedge(prev1);
-      else if ((ic1 != NULL) &&
+      else if ((ic1 != nullptr) &&
                ((ic1->halfedge() == he1) || (ic1->halfedge() == he2)))
         ic1->set_halfedge(prev1);
 
@@ -4565,7 +4565,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
         if ((v1->parameter_space_in_x() != ARR_INTERIOR) ||
             (v1->parameter_space_in_y() != ARR_INTERIOR))
         {
-          v1->set_halfedge(NULL);    // disconnect the end vertex
+          v1->set_halfedge(nullptr);    // disconnect the end vertex
           _remove_vertex_if_redundant(v1, f1);
         }
         else {
@@ -4598,7 +4598,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
     prev1 = he1->prev();
     prev2 = he2->prev();
 
-    if ((ic1 != NULL) && (ic1 == ic2)) {
+    if ((ic1 != nullptr) && (ic1 == ic2)) {
 
       // If both halfedges lie on the same inner component (hole) inside the
       // face (case 3.1), we have to split this component into two holes.
@@ -4639,7 +4639,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
     }
     else if (oc1 != oc2) {
       // RWRW: NEW!
-      CGAL_assertion((oc1 != NULL) && (oc2 != NULL));
+      CGAL_assertion((oc1 != nullptr) && (oc2 != nullptr));
 
       // In case both halfegdes he1 and he2 are incident to the same face
       // but lie on different outer CCBs of this face, removing this pair of
@@ -4665,7 +4665,7 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
       add_inner_ccb = true;
     }
     else {
-      CGAL_assertion((oc1 != NULL) && (oc1 == oc2));
+      CGAL_assertion((oc1 != nullptr) && (oc1 == oc2));
 
       // If both halfedges are incident to the same outer CCB of their
       // face (case 3.2), we have to distinguish two sub-cases:
@@ -4851,9 +4851,9 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
   prev1 = he1->prev();
   prev2 = he2->prev();
 
-  CGAL_assertion((ic1 == NULL) || (ic2 == NULL));
+  CGAL_assertion((ic1 == nullptr) || (ic2 == nullptr));
 
-  if ((ic1 == NULL) && (ic2 == NULL)) {
+  if ((ic1 == nullptr) && (ic2 == nullptr)) {
     bool add_inner_ccb = false;
 
     // Comment EFEF 2013-05-31: if we ever find the need to use signs1 and
@@ -5017,15 +5017,15 @@ _remove_edge(DHalfedge* e, bool remove_source, bool remove_target)
   // inside it (case 3.3). We first make sure that f1 contains the hole f2, so
   // we can merge f2 with it (we swap roles between the halfedges if
   // necessary).
-  if (ic2 != NULL) {
+  if (ic2 != nullptr) {
     he1 = he2;
     he2 = he1->opposite();
 
     ic1 = ic2;
-    ic2 = NULL;
+    ic2 = nullptr;
 
     oc2 = oc1;
-    oc1 = NULL;
+    oc1 = nullptr;
 
     DFace* tf = f1;
     f1 = f2;
@@ -5139,7 +5139,7 @@ _remove_vertex_if_redundant(DVertex* v, DFace* f)
 
   // In case the vertex has no incident halfedges, remove it if it is
   // redundant. Otherwise, make it an isolated vertex.
-  if (v->halfedge() == NULL) {
+  if (v->halfedge() == nullptr) {
     if (m_topol_traits.is_redundant(v)) {
       // Remove the vertex and notify the observers on doing so.
       _notify_before_remove_vertex(Vertex_handle(v));

Arrangement_on_surface_2/include/CGAL/Arrangement_2/Arrangement_zone_2_impl.h

@@ -106,7 +106,7 @@ void Arrangement_zone_2<Arrangement, ZoneVisitor>::compute_zone()
   const Halfedge_const_handle* hh;
   const Face_const_handle* fh;
 
-  if ((vh = object_cast<Vertex_const_handle>(&m_obj)) != NULL) {
+  if ((vh = object_cast<Vertex_const_handle>(&m_obj)) != nullptr) {
     CGAL_assertion(m_has_left_pt);
 
     // The left endpoint coincides with an existing vertex:
@@ -128,7 +128,7 @@ void Arrangement_zone_2<Arrangement, ZoneVisitor>::compute_zone()
 #endif
 
   }
-  else if ((hh = object_cast<Halfedge_const_handle>(&m_obj)) != NULL) {
+  else if ((hh = object_cast<Halfedge_const_handle>(&m_obj)) != nullptr) {
     if (m_has_left_pt) {
       // Obtain the right halfedge from the halfedge-pair containing m_left_pt
       // in their interior.
@@ -171,7 +171,7 @@ void Arrangement_zone_2<Arrangement, ZoneVisitor>::compute_zone()
     // The left endpoint lies inside a face.
     fh = object_cast<Face_const_handle>(&m_obj);
 
-    CGAL_assertion_msg(fh != NULL,
+    CGAL_assertion_msg(fh != nullptr,
                        "Invalid object returned by the point-location query.");
 
     // Compute the zone of the curve at the interior of the face.
@@ -843,7 +843,7 @@ _compute_next_intersection(Halfedge_handle he,
         // valid, as they lie to its right.
         valid_intersection = true;
       }
-      else if (ip != NULL) {
+      else if (ip != nullptr) {
         if (m_has_right_pt && m_right_on_boundary &&
             m_geom_traits->equal_2_object()(ip->first, m_right_pt))
         {
@@ -861,7 +861,7 @@ _compute_next_intersection(Halfedge_handle he,
       else {
         // We have an overlapping subcurve.
         icv = object_cast<X_monotone_curve_2>(&(inter_list.front()));
-        CGAL_assertion(icv != NULL);
+        CGAL_assertion(icv != nullptr);
 
         if (m_geom_traits->is_closed_2_object()(*icv, ARR_MIN_END)) {
           // The curve has a valid left point - make sure it lies to the
@@ -905,7 +905,7 @@ _compute_next_intersection(Halfedge_handle he,
     // Compare that current object with m_left_pt (if exists).
     ip = object_cast<Intersect_point_2>(&(inter_list.front()));
 
-    if (ip != NULL) {
+    if (ip != nullptr) {
       // We have a simple intersection point - if we don't have to skip it,
       // make sure it lies to the right of m_left_pt (if m_left_pt is on the
       // left boundary, all points lie to it right).
@@ -930,7 +930,7 @@ _compute_next_intersection(Halfedge_handle he,
     else {
       // We have an overlapping subcurve.
       icv = object_cast<X_monotone_curve_2>(&(inter_list.front()));
-      CGAL_assertion(icv != NULL);
+      CGAL_assertion(icv != nullptr);
 
       if (m_geom_traits->is_closed_2_object()(*icv, ARR_MIN_END)) {
         // The curve has a valid left point - make sure it lies to the
@@ -1122,7 +1122,7 @@ _leftmost_intersection(Ccb_halfedge_circulator he_curr, bool on_boundary,
     // We have found an intersection (either a simple point or an
     // overlapping x-monotone curve).
     const Intersect_point_2* int_p = object_cast<Intersect_point_2>(&iobj);
-    if (int_p != NULL) {
+    if (int_p != nullptr) {
       Point_2 ip = int_p->first;
 
       // Found a simple intersection point. Check if it is the leftmost
@@ -1144,7 +1144,7 @@ _leftmost_intersection(Ccb_halfedge_circulator he_curr, bool on_boundary,
       // We have located an overlapping curve. Assign ip as its left
       // endpoint.
       const X_monotone_curve_2* icv = object_cast<X_monotone_curve_2>(&iobj);
-      CGAL_assertion(icv != NULL);
+      CGAL_assertion(icv != nullptr);
       Point_2 ip = min_vertex(*icv);
 
       // Check if this endpoint it is the leftmost intersection point so far.
@@ -1301,7 +1301,7 @@ _zone_in_face(Face_handle face, bool on_boundary)
     m_cv = m_sub_cv2;
   }
 
-  const X_monotone_curve_2*p_orig_curve = NULL;
+  const X_monotone_curve_2*p_orig_curve = nullptr;
 
   if (! m_found_iso_vert) {
     // Check whether m_intersect_p coincides with one of the end-vertices of the
@@ -1364,8 +1364,8 @@ _zone_in_face(Face_handle face, bool on_boundary)
       // subcurves that result from splitting m_intersect_he->curve() at the
       // intersection point we have just detected, one extends to the left
       // and one to the right of this split point.
-      const X_monotone_curve_2* p_left_subcurve = NULL;
+      const X_monotone_curve_2* p_left_subcurve = nullptr;
-      const X_monotone_curve_2* p_right_subcurve = NULL;
+      const X_monotone_curve_2* p_right_subcurve = nullptr;
 
       if (inserted_he->next()->direction() == ARR_LEFT_TO_RIGHT) {
         // The next halfedge extends to the right of the split point:

Arrangement_on_surface_2/include/CGAL/Arrangement_2/graph_traits_dual.h

@@ -247,7 +247,7 @@ public:
   typedef Face_neighbor_iterator            Incident_edge_iterator;
 
   /*! Default constructor. */
-  Dual_arrangement_on_surface() : p_arr(NULL) {}
+  Dual_arrangement_on_surface() : p_arr(nullptr) {}
 
   /*! Constructor from an arrangement. */
   Dual_arrangement_on_surface(const Arrangement& arr) :

Arrangement_on_surface_2/include/CGAL/Arrangement_on_surface_2.h

@@ -165,7 +165,7 @@ protected:
     const Topology_traits* m_topol_traits;
 
   public:
-    _Is_concrete_vertex() : m_topol_traits(NULL) {}
+    _Is_concrete_vertex() : m_topol_traits(nullptr) {}
 
     _Is_concrete_vertex(const Topology_traits* topol_traits) :
       m_topol_traits(topol_traits)
@@ -173,7 +173,7 @@ protected:
 
     bool operator()(const DVertex& v) const
     {
-      if (m_topol_traits == NULL)
+      if (m_topol_traits == nullptr)
         return true;
 
       return (m_topol_traits->is_concrete_vertex(&v));
@@ -188,7 +188,7 @@ protected:
     const Topology_traits* m_topol_traits;
 
   public:
-    _Is_valid_vertex() : m_topol_traits(NULL) {}
+    _Is_valid_vertex() : m_topol_traits(nullptr) {}
 
     _Is_valid_vertex(const Topology_traits* topol_traits) :
       m_topol_traits(topol_traits)
@@ -196,7 +196,7 @@ protected:
 
     bool operator()(const DVertex& v) const
     {
-      if (m_topol_traits == NULL)
+      if (m_topol_traits == nullptr)
         return true;
 
       return (m_topol_traits->is_valid_vertex(&v));
@@ -211,7 +211,7 @@ protected:
     const Topology_traits* m_topol_traits;
 
   public:
-    _Is_valid_halfedge() : m_topol_traits(NULL) {}
+    _Is_valid_halfedge() : m_topol_traits(nullptr) {}
 
     _Is_valid_halfedge(const Topology_traits* topol_traits) :
       m_topol_traits(topol_traits)
@@ -219,7 +219,7 @@ protected:
 
     bool operator()(const DHalfedge& he) const
     {
-      if (m_topol_traits == NULL)
+      if (m_topol_traits == nullptr)
         return true;
 
       return (m_topol_traits->is_valid_halfedge(&he));
@@ -234,7 +234,7 @@ protected:
     const Topology_traits* m_topol_traits;
 
   public:
-    _Is_valid_face() : m_topol_traits(NULL) {}
+    _Is_valid_face() : m_topol_traits(nullptr) {}
 
     _Is_valid_face(const Topology_traits* topol_traits) :
       m_topol_traits(topol_traits)
@@ -242,7 +242,7 @@ protected:
 
     bool operator()(const DFace& f) const
     {
-      if (m_topol_traits == NULL)
+      if (m_topol_traits == nullptr)
         return true;
 
       return (m_topol_traits->is_valid_face(&f));
@@ -257,7 +257,7 @@ protected:
     const Topology_traits* m_topol_traits;
 
   public:
-    _Is_unbounded_face() : m_topol_traits(NULL) {}
+    _Is_unbounded_face() : m_topol_traits(nullptr) {}
 
     _Is_unbounded_face(const Topology_traits* topol_traits) :
       m_topol_traits(topol_traits)
@@ -587,7 +587,7 @@ public:
       const DHalfedge* he_curr = he_first;
       Size n = 0;
 
-      if (he_curr != NULL) {
+      if (he_curr != nullptr) {
         do {
           ++n;
           he_curr = he_curr->next()->opposite();
@@ -1777,7 +1777,7 @@ protected:
    * \return A pointer to a halfedge whose target is v, where cv should be
    *         inserted between this halfedge and the next halfedge around this
    *         vertex (in a clockwise order).
-   *         A NULL return value indicates a precondition violation.
+   *         A nullptr return value indicates a precondition violation.
    */
   DHalfedge* _locate_around_vertex(DVertex* v, const X_monotone_curve_2& cv,
                                    Arr_curve_end ind) const;
@@ -2031,7 +2031,7 @@ protected:
    * \param bx The boundary condition at the x-coordinate.
    * \param by The boundary condition at the y-coordinate.
    * \param p_pred Output: The predecessor halfedge around this vertex
-   *                       (may be NULL, if no such halfedge exists).
+   *                       (may be nullptr, if no such halfedge exists).
    * \return The vertex that corresponds to the curve end.
    */
   DVertex* _place_and_set_curve_end(DFace* f,

Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h

@@ -186,7 +186,7 @@ public:
     m_invalid_he()
   {
     m_geom_traits = static_cast<const Traits_adaptor_2*>(arr.geometry_traits());
-    CGAL_assertion(visitor != NULL);
+    CGAL_assertion(visitor != nullptr);
 
     // Initialize the visitor.
     visitor->init(&arr);

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Arc_2.h

@@ -960,9 +960,9 @@ public:
 
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_x_at_limit_2,
                                             compare_x_at_limit_2)
-        // compare with NULL, in order to avoid a performance warning with VC++
+        // compare with nullptr, in order to avoid a performance warning with VC++
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_x_at_limit_2(
                 p, *dynamic_cast< const Kernel_arc_2* >(this), ce
         );
@@ -990,7 +990,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_x_at_limit_2,
                                             compare_x_at_limit_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_x_at_limit_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), ce1, cv2, ce2
         );
@@ -1017,7 +1017,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_x_near_limit_2,
                                             compare_x_near_limit_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_x_near_limit_2(
                 p, *dynamic_cast< const Kernel_arc_2* >(this), ce
         );
@@ -1043,7 +1043,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_x_near_limit_2,
                                             compare_x_near_limit_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_x_near_limit_2(*dynamic_cast< const Kernel_arc_2* >(this), cv2, ce);
     }
 
@@ -1068,7 +1068,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_y_near_boundary_2,
                                             compare_y_near_boundary_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_y_near_boundary_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), cv2, ce
         );
@@ -1090,7 +1090,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_y_at_x_2,
                                             compare_y_at_x_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_y_at_x_2(p, *dynamic_cast< const Kernel_arc_2* >(this));
     }
 
@@ -1116,7 +1116,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_y_at_x_left_2,
                                             compare_y_at_x_left_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_y_at_x_left_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), cv2, p
         );
@@ -1144,7 +1144,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Compare_y_at_x_right_2,
                                             compare_y_at_x_right_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return compare_y_at_x_right_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), cv2, p
         );
@@ -1161,18 +1161,18 @@ public:
      * \return \c true, if p.x() is in x-range of arc, \c false otherwise
      */
     bool is_in_x_range(const Coordinate_1& x,
-                       bool *eq_min = NULL, bool *eq_max = NULL) const {
+                       bool *eq_min = nullptr, bool *eq_max = nullptr) const {
 
-        if (eq_min != NULL && eq_max != NULL) {
+        if (eq_min != nullptr && eq_max != nullptr) {
             *eq_min = *eq_max = false;
         }
 
         if (is_vertical()) {
             if (x == this->x()) {
-                if (eq_min != NULL) {
+                if (eq_min != nullptr) {
                     *eq_min = true;
                 }
-                if (eq_max != NULL) {
+                if (eq_max != nullptr) {
                     *eq_max = true;
                 }
                 return true;
@@ -1191,7 +1191,7 @@ public:
         if (min_has_x) {
             resmin = Curved_kernel_via_analysis_2::instance().
                 kernel().compare_1_object()(x, _minpoint().x());
-            if (eq_min != NULL) { // TODO asymptotic end in x-range?
+            if (eq_min != nullptr) { // TODO asymptotic end in x-range?
                 *eq_min = (resmin == CGAL::EQUAL);
             }
         }
@@ -1206,7 +1206,7 @@ public:
         if (max_has_x) {
             resmax = Curved_kernel_via_analysis_2::instance().
                 kernel().compare_1_object()(x, _maxpoint().x());
-            if (eq_max != NULL) { // TODO asymptotic end in x-range?
+            if (eq_max != nullptr) { // TODO asymptotic end in x-range?
                 *eq_max = (resmax == CGAL::EQUAL);
             }
         }
@@ -1246,7 +1246,7 @@ public:
                                             equal_2)
 
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return equal_2(*dynamic_cast< const Kernel_arc_2* >(this), cv2);
     }
 
@@ -1262,7 +1262,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Do_overlap_2,
                                             do_overlap_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return do_overlap_2(*dynamic_cast< const Kernel_arc_2* >(this), cv2);
     }
 
@@ -1345,7 +1345,7 @@ public:
                                             intersect_2)
 
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return intersect_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), cv2, oi
         );
@@ -1449,7 +1449,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Trim_2, trim_2)
 
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return trim_2(*dynamic_cast< const Kernel_arc_2* >(this), p, q);
     }
 
@@ -1467,7 +1467,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Split_2,
                                             split_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         split_2(*dynamic_cast< const Kernel_arc_2* >(this), p, s1, s2);
     }
 
@@ -1483,7 +1483,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Are_mergeable_2,
                                             are_mergeable_2)
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         return are_mergeable_2(
                 *dynamic_cast< const Kernel_arc_2* >(this), cv2
         );
@@ -1503,7 +1503,7 @@ public:
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_ARC(Merge_2, merge_2)
         Kernel_arc_2 tmp;
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
         merge_2(*dynamic_cast< const Kernel_arc_2* >(this), cv2, tmp);
         return tmp;
     }
@@ -1653,7 +1653,7 @@ public:
                      Kernel_arc_2& trimmed2) const {
 
         CGAL_precondition(Kernel_arc_2_equals_Arc_2 ||
-                          dynamic_cast< const Kernel_arc_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_arc_2* >(this) != nullptr);
 
         const Kernel_arc_2& cv1 = static_cast< const Kernel_arc_2& >(*this);
 
@@ -1956,7 +1956,7 @@ protected:
 
         CGAL_precondition(!is_on_bottom_top(where));
         CGAL_assertion(Kernel_arc_2_equals_Arc_2 ||
-                       dynamic_cast< const Kernel_arc_2*>(this) != NULL);
+                       dynamic_cast< const Kernel_arc_2*>(this) != nullptr);
         Kernel_arc_2::simplify(*dynamic_cast< const Kernel_arc_2*>(this), cv2);
         if(curve().is_identical(cv2.curve()))
             return CGAL::sign(arcno() - cv2.arcno());

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Curve_renderer_facade.h

@@ -262,8 +262,8 @@ public:
         class Allocator >
     inline void draw(const Arc_2& arc, 
             Container< std::vector< Coord_2 >, Allocator >& pts,
-            boost::optional< Coord_2 > *end_pt1 = NULL, 
+            boost::optional< Coord_2 > *end_pt1 = nullptr, 
-            boost::optional< Coord_2 > *end_pt2 = NULL) {
+            boost::optional< Coord_2 > *end_pt2 = nullptr) {
 
 #ifndef CGAL_CKVA_DUMMY_RENDERER
         Bbox_2 bbox;

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Curved_kernel_via_analysis_2_functors.h

@@ -93,7 +93,7 @@ public:
     Curved_kernel_via_analysis_2_functor_base(
             Curved_kernel_via_analysis_2 *kernel) :
         _m_curved_kernel(kernel) {
-        CGAL_precondition(kernel != NULL);
+        CGAL_precondition(kernel != nullptr);
     }
 
     //!@}

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Make_x_monotone_2.h

@@ -108,7 +108,7 @@ struct Make_x_monotone_2 :
      */
     Make_x_monotone_2(Curved_kernel_via_analysis_2 *kernel) :
         _m_curved_kernel(kernel) {
-        CGAL_assertion(kernel != NULL);
+        CGAL_assertion(kernel != nullptr);
     }
 
     //!@}

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Point_2.h

@@ -504,7 +504,7 @@ public:
 
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_POINT(Compare_x_2, compare_x_2)
         CGAL_precondition(Kernel_point_2_equals_Point_2 ||
-                          dynamic_cast< const Kernel_point_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_point_2* >(this) != nullptr);
         return compare_x_2(*dynamic_cast< const Kernel_point_2* >(this), q);
     }
 
@@ -527,7 +527,7 @@ public:
 
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_POINT(Compare_xy_2, compare_xy_2)
         CGAL_precondition(Kernel_point_2_equals_Point_2 ||
-                          dynamic_cast< const Kernel_point_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_point_2* >(this) != nullptr);
         return compare_xy_2(
                 *dynamic_cast< const Kernel_point_2* >(this), q, equal_x
         );
@@ -547,7 +547,7 @@ public:
 
         CGAL_CKvA_2_GRAB_CK_FUNCTOR_FOR_POINT(Is_on_2, is_on_2)
         CGAL_precondition(Kernel_point_2_equals_Point_2 ||
-                          dynamic_cast< const Kernel_point_2* >(this) != NULL);
+                          dynamic_cast< const Kernel_point_2* >(this) != nullptr);
         return is_on_2(*dynamic_cast< const Kernel_point_2* >(this), curve);
     }
 

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/Sweep_curves_adapter_2.h

@@ -66,7 +66,7 @@ public:
     //! standard constructor
     Compare_xy_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     result_type operator()(const Point_2& p1, const Point_2& p2) const {
@@ -170,7 +170,7 @@ public:
     //! standard constructor
     Less_xy_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!
@@ -196,7 +196,7 @@ public:
     //! standard constructor
     Compare_y_at_x_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     result_type operator()(const Arc_2& cv, const Point_2& p) const {
@@ -322,7 +322,7 @@ public:
     //! standard constructor
     Equal_y_at_x_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!
@@ -425,7 +425,7 @@ public:
     //! standard constructor
     Source_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!
@@ -452,7 +452,7 @@ public:
     //! standard constructor
     Target_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!
@@ -548,7 +548,7 @@ public:
     //! standard constructor
     New_endpoints_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!\brief
@@ -646,7 +646,7 @@ public:
     //! standard constructor
     Intersect_right_of_point_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!\brief
@@ -699,7 +699,7 @@ public:
     //! standard constructor
     Make_x_monotone_2(SweepCurvesAdapter_2 *adapter) :
         _m_adapter(adapter) {
-        CGAL_assertion(adapter != NULL);
+        CGAL_assertion(adapter != nullptr);
     }
 
     /*!

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_2.h

@@ -288,7 +288,7 @@ public:
     //! \brief returns the drawing window and resolution 
     void get_setup_parameters(CGAL::Bbox_2 *pbox, int& res_w_, 
                 int& res_h_) const {
-        if(pbox != NULL)
+        if(pbox != nullptr)
             *pbox = engine.window;
         res_w_ = engine.res_w; 
         res_h_ = engine.res_h;
@@ -332,7 +332,7 @@ private:
     
     //! computes pixel coordinates from rational point
     void get_pixel_coords(const Rational& x, const Rational& y, 
-            Pixel_2& pix, Rational *ppix_x=NULL, Rational *ppix_y=NULL)
+            Pixel_2& pix, Rational *ppix_x=nullptr, Rational *ppix_y=nullptr)
     {
         Rational p_x = (x - engine.x_min_r) / engine.pixel_w_r,
                  p_y = (y - engine.y_min_r) / engine.pixel_h_r;
@@ -344,7 +344,7 @@ private:
         pix.x = static_cast<int>(std::floor(CGAL::to_double(p_x)));
         pix.y = static_cast<int>(std::floor(CGAL::to_double(p_y)));   
 
-        if(ppix_x != NULL && ppix_y != NULL) {
+        if(ppix_x != nullptr && ppix_y != nullptr) {
             *ppix_x = p_x;
             *ppix_y = p_y;
         }
@@ -428,8 +428,8 @@ template < class Coord_2, template < class, class > class Container,
         class Allocator >
 void draw(const Arc_2& arc, 
           Container< std::vector< Coord_2 >, Allocator >& points,
-          boost::optional< Coord_2 > *end_pt1 = NULL, 
+          boost::optional< Coord_2 > *end_pt1 = nullptr, 
-          boost::optional< Coord_2 > *end_pt2 = NULL) {
+          boost::optional< Coord_2 > *end_pt2 = nullptr) {
 
 #ifdef CGAL_CKVA_CR_TIMING
     refine_timer.start();
@@ -616,7 +616,7 @@ void draw(const Arc_2& arc,
 #endif
 
 #ifdef CGAL_CKVA_RENDER_WITH_REFINEMENT
-    if(end_pt1 != NULL && loc_p1 == CGAL::ARR_INTERIOR && 
+    if(end_pt1 != nullptr && loc_p1 == CGAL::ARR_INTERIOR && 
          (clip_src || y_lower < engine.y_min_r || y_lower > engine.y_max_r)) {
         y_lower0 = (clip_src ? 
             get_endpoint_y(arc, lower0, CGAL::ARR_MIN_END, false,
@@ -626,7 +626,7 @@ void draw(const Arc_2& arc,
         *end_pt1 = Coord_2(CGAL::to_double(lower0), 
                 CGAL::to_double(y_lower0));  
     }
-    if(end_pt2 != NULL && loc_p2 == CGAL::ARR_INTERIOR && 
+    if(end_pt2 != nullptr && loc_p2 == CGAL::ARR_INTERIOR && 
          (clip_tgt || y_upper < engine.y_min_r || y_upper > engine.y_max_r)) { 
         y_upper0 = (clip_tgt ? 
             get_endpoint_y(arc, upper0, CGAL::ARR_MAX_END, false,
@@ -650,9 +650,9 @@ void draw(const Arc_2& arc,
     get_pixel_coords(upper, y_upper, pix_2);  
     
 #ifndef CGAL_CKVA_RENDER_WITH_REFINEMENT
-    if(end_pt1 != NULL)
+    if(end_pt1 != nullptr)
         *end_pt1 = Coord_2(pix_1.x, pix_1.y);
-    if(end_pt2 != NULL)
+    if(end_pt2 != nullptr)
         *end_pt2 = Coord_2(pix_2.x, pix_2.y);
 #endif
     

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_internals.h

@@ -321,11 +321,11 @@ public:
     
     //! \brief evalutates a polynomial at certain x-coordinate
     static NT evaluate(const Poly_1& poly, const NT& x, 
-        bool *error_bounds_ = NULL)
+        bool *error_bounds_ = nullptr)
     {
         typename Renderer_traits::Extract_eval extract;
         int n = poly.degree()+1, m = (n-1)>>1, odd = n&1;
-        if(error_bounds_ != NULL)
+        if(error_bounds_ != nullptr)
             *error_bounds_ = false;
         if(n == 1)
             return extract(poly.lcoeff(), error_bounds_);
@@ -479,7 +479,7 @@ bool setup(const CGAL::Bbox_2& box_, int res_w_, int res_h_)
     pixel_w = (x_max - x_min) / res_w;
     pixel_h = (y_max - y_min) / res_h;
 
-    //srand(time(NULL));
+    //srand(time(nullptr));
     // from 0.1 to 0.5
     double rmin = 0.1, rmax = 0.5;
     NT sx = pixel_w * static_cast<NT>(rmin + 

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Curve_renderer_traits.h

@@ -223,8 +223,8 @@ struct Curve_renderer_traits_base
         typedef Coeff result_type;
         
         Coeff operator()(const Coeff& x, 
-            bool *error_bounds = NULL) const { 
+            bool *error_bounds = nullptr) const { 
-            if(error_bounds != NULL)
+            if(error_bounds != nullptr)
                  *error_bounds = false;
             return x;
         }
@@ -309,13 +309,13 @@ struct Curve_renderer_traits<CGAL::Interval_nt<true>, CORE::BigRat > :
         typedef Float result_type;
         
         Float operator()(const Coeff& x, 
-                    bool *error_bounds = NULL) const { 
+                    bool *error_bounds = nullptr) const { 
             bool err_bnd;
 //             err_bnd = (CGAL_ABS(l) < 1E-15 || CGAL_ABS(u) < 1E-15) ||
 //                 ((l <= 0 && u >= 0));
             Float l = x.inf(), u = x.sup(), mid = (l+u)/2;
             err_bnd = ((l < 0 && u > 0)||(l == 0 && u == 0));
-            if(error_bounds != NULL)
+            if(error_bounds != nullptr)
                 *error_bounds = err_bnd;
 //! ATTENTION!!! if smth is screwed up try to uncomment the line below
 //! this is very crucial for performance & stability
@@ -456,13 +456,13 @@ struct Curve_renderer_traits<CGAL::Interval_nt<true>, leda::rational > :
         typedef Float result_type;
         
         Float operator()(const Coeff& x, 
-                    bool *error_bounds = NULL) const { 
+                    bool *error_bounds = nullptr) const { 
             bool err_bnd;
 //             err_bnd = (CGAL_ABS(l) < 1E-15 || CGAL_ABS(u) < 1E-15) ||
 //                 ((l <= 0 && u >= 0));
             Float l = x.inf(), u = x.sup(), mid = (l+u)/2;
             err_bnd = ((l < 0 && u > 0)||(l == 0 && u == 0));
-            if(error_bounds != NULL)
+            if(error_bounds != nullptr)
                 *error_bounds = err_bnd;
 //! ATTENTION!!! if smth is screwed up try to uncomment the line below
 //! this is very crucial for performance & stability

Arrangement_on_surface_2/include/CGAL/Curved_kernel_via_analysis_2/gfx/Subdivision_2.h

@@ -243,7 +243,7 @@ private:
 template <class NT, class Algebraic_curve_2_>
 void Subdivision_2<NT, Algebraic_curve_2_>::draw(QPainter *painter_)
 {
-	if(!initialized||!polynomial_set||painter_==NULL)
+	if(!initialized||!polynomial_set||painter_==nullptr)
 		return;
 	painter = painter_;
 	//std::cout << " P(x(y)): " << coeffs_x << std::endl; 

Arrangement_on_surface_2/include/CGAL/IO/Arr_text_formatter.h

@@ -76,19 +76,19 @@ public:
 
   /*! Default constructor.*/
   Arr_text_formatter():
-    m_out(NULL),
+    m_out(nullptr),
-    m_in(NULL)
+    m_in(nullptr)
   {}
 
   /*! Construct an output formatter. */
   Arr_text_formatter(std::ostream& os) :
     m_out(&os),
-    m_in(NULL)
+    m_in(nullptr)
   {}
 
   /*! Construct an input formatter. */
   Arr_text_formatter(std::istream& is) :
-    m_out(NULL),
+    m_out(nullptr),
     m_in(&is)
   {}
 
@@ -111,14 +111,14 @@ public:
   /*! Get the output stream. */
   inline std::ostream& out()
   {
-    CGAL_assertion(m_out != NULL);
+    CGAL_assertion(m_out != nullptr);
     return (*m_out);
   }
 
   /*! Get the input stream. */
   inline std::istream& in()
   {
-    CGAL_assertion(m_in != NULL);
+    CGAL_assertion(m_in != nullptr);
     return (*m_in);
   }
 
@@ -128,7 +128,7 @@ public:
   /*! Write a begin-arrangement comment. */
   void write_arrangement_begin()
   {
-    CGAL_assertion(m_out != NULL);
+    CGAL_assertion(m_out != nullptr);
     m_old_out_mode = get_mode(*m_out);
     set_ascii_mode(*m_out);
     _write_comment("BEGIN ARRANGEMENT");
@@ -285,7 +285,7 @@ public:
   /*! Start reading an arrangement. */
   void read_arrangement_begin() 
   {
-    CGAL_assertion(m_in != NULL);
+    CGAL_assertion(m_in != nullptr);
     m_old_in_mode = get_mode(*m_in);
     set_ascii_mode(*m_in);
     _skip_comments();
@@ -299,7 +299,7 @@ public:
   }
 
   /*! Read a size value (with a label comment line before it). */
-  Size read_size(const char* /* title */ = NULL)
+  Size read_size(const char* /* title */ = nullptr)
   {
     std::size_t   val;
 
@@ -448,7 +448,7 @@ protected:
   /*! Skip until end of line. */
   void _skip_until_EOL() 
   {
-    CGAL_assertion(m_in != NULL);
+    CGAL_assertion(m_in != nullptr);
 
     int     c;
     while ((c = m_in->get()) != EOF && c != '\n') {};
@@ -457,7 +457,7 @@ protected:
   /*! Skip comment lines. */
   void _skip_comments() 
   {
-    CGAL_assertion(m_in != NULL);
+    CGAL_assertion(m_in != nullptr);
 
     int     c = m_in->get();
     if (c == ' ')

Arrangement_on_surface_2/include/CGAL/IO/Arrangement_2_reader.h

@@ -124,7 +124,7 @@ namespace CGAL {
       formatter.read_vertices_end();
 
       // Read the DCEL halfedges and store them in the halfedges vector.
-      DHalfedge* he = NULL;
+      DHalfedge* he = nullptr;
       formatter.read_edges_begin();
 
       m_halfedges.resize(number_of_halfedges);
@@ -179,7 +179,7 @@ namespace CGAL {
       else
       {
         // Allocate a vertex at infinity.
-        new_v = m_arr_access.new_vertex(NULL, ps_x, ps_y);
+        new_v = m_arr_access.new_vertex(nullptr, ps_x, ps_y);
       }
 
       formatter.read_vertex_end();
@@ -213,7 +213,7 @@ namespace CGAL {
       else
       {
         // Allocate a new fictitious edge.
-        new_he = m_arr_access.new_edge(NULL);
+        new_he = m_arr_access.new_edge(nullptr);
       }
 
       // Set the cross pointers between the twin halfedges and the end vertices.
@@ -276,7 +276,7 @@ namespace CGAL {
 
         // Read the current outer CCB.
         n = formatter.read_size("halfedges_on_outer_ccb");
-        he = _read_ccb(formatter, n, new_occb, NULL);
+        he = _read_ccb(formatter, n, new_occb, nullptr);
         new_f->add_outer_ccb(new_occb, he);
       }
       formatter.read_outer_ccbs_end();
@@ -293,7 +293,7 @@ namespace CGAL {
 
         // Read the current inner CCB.
         n = formatter.read_size("halfedges_on_inner_ccb");
-        he = _read_ccb(formatter, n, NULL, new_iccb);
+        he = _read_ccb(formatter, n, nullptr, new_iccb);
         new_f->add_inner_ccb(new_iccb, he);
       }
       formatter.read_inner_ccbs_end();
@@ -331,7 +331,7 @@ namespace CGAL {
      * \param boundary_size The number of halfedges along the boundary.
      * \param p_outer The outer CCB.
      * \param p_inner The inner CCB.
-     * \pre p_outer is valid and p_inner is NULL, or vice versa.
+     * \pre p_outer is valid and p_inner is nullptr, or vice versa.
      * \return A pointer to the first halfedge read.
      */
     template <class Formatter>
@@ -340,8 +340,8 @@ namespace CGAL {
                          DOuter_ccb* p_outer,
                          DInner_ccb* p_inner)
     {
-      CGAL_assertion((p_outer != NULL && p_inner == NULL) ||
+      CGAL_assertion((p_outer != nullptr && p_inner == nullptr) ||
-                     (p_outer == NULL && p_inner != NULL));
+                     (p_outer == nullptr && p_inner != nullptr));
 
       formatter.read_ccb_halfedges_begin();
  
@@ -349,7 +349,7 @@ namespace CGAL {
       std::size_t  first_idx = formatter.read_halfedge_index();
       DHalfedge*   first_he = m_halfedges [first_idx];
 
-      if (p_outer != NULL)
+      if (p_outer != nullptr)
         first_he->set_outer_ccb(p_outer);
       else
         first_he->set_inner_ccb(p_inner);
@@ -369,7 +369,7 @@ namespace CGAL {
         prev_he->set_next(curr_he);
 
         // Set the CCB.
-        if (p_outer != NULL)
+        if (p_outer != nullptr)
           curr_he->set_outer_ccb(p_outer);
         else
           curr_he->set_inner_ccb(p_inner);

Arrangement_on_surface_2/include/CGAL/IO/Arrangement_2_writer.h

@@ -91,7 +91,7 @@ namespace CGAL {
     /*! Constructor. */
     Arrangement_2_writer(const Arrangement_2& arr) :
       m_arr(arr),
-      m_dcel(NULL),
+      m_dcel(nullptr),
       m_curr_v(0),
       m_curr_he(0)
     {
@@ -328,7 +328,7 @@ namespace CGAL {
     /*! Get the number of edges along a given CCB. */
     std::size_t _circulator_size(const DHalfedge* ccb) const
     {
-      CGAL_assertion(ccb != NULL);
+      CGAL_assertion(ccb != nullptr);
 
       std::size_t       n = 0;
       const DHalfedge*  curr = ccb;

Arrangement_on_surface_2/include/CGAL/IO/Fig_stream.h

@@ -1128,7 +1128,7 @@ public:
   {
     CGAL_precondition (_ofile.is_open());
 
-    if (text == NULL || strlen(text) == 0)
+    if (text == nullptr || strlen(text) == 0)
       return;
 
     _write_text (pos, 

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_insertion_ss_visitor.h

@@ -116,7 +116,7 @@ template <typename Hlpr, typename Vis>
 bool Arr_insertion_ss_visitor<Hlpr, Vis>::
 is_split_event(Subcurve* sc, Event* event)
 {
-  if (sc->last_curve().halfedge_handle() == Halfedge_handle(NULL)) return false;
+  if (sc->last_curve().halfedge_handle() == Halfedge_handle(nullptr)) return false;
 
   if (! sc->originating_subcurve1())
     return (sc->left_event() != this->current_event());

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_insertion_traits_2.h

@@ -127,7 +127,7 @@ public:
       // X_monotone_curve_2
       for(; oi != oi_end; ++oi) {
         base_overlap_cv = object_cast<Base_x_monotone_curve_2>(&(*oi));
-        if (base_overlap_cv != NULL) {
+        if (base_overlap_cv != nullptr) {
           // Add halfedge handles to the resulting curve.
           Halfedge_handle he;
 
@@ -144,7 +144,7 @@ public:
           intersect_p =
             object_cast<std::pair<Base_point_2, unsigned int> >(&(*oi));
 
-          CGAL_assertion (intersect_p != NULL);
+          CGAL_assertion (intersect_p != nullptr);
 
           *oi = make_object(std::make_pair(Point_2(intersect_p->first),
                                            intersect_p->second));

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_overlay_ss_visitor.h

@@ -457,19 +457,19 @@ after_handle_event(Event* event, Status_line_iterator iter, bool flag)
   // point, we update the top fictitious halfedges for all subcurves incident
   // to this event.
   Event_subcurve_reverse_iterator rev_iter = event->right_curves_rbegin();
-  Subcurve* sc_above = NULL;
+  Subcurve* sc_above = nullptr;
 
   if (iter != this->status_line_end())
     sc_above = (*iter);
 
-  if (sc_above == NULL) {
+  if (sc_above == nullptr) {
     if (rev_iter != event->right_curves_rend()) {
       if ((*rev_iter)->color() == Gt2::BLUE)
         (*rev_iter)->set_red_top_face(m_overlay_helper.red_top_face());
       else if ((*rev_iter)->color() == Gt2::RED)
         (*rev_iter)->set_blue_top_face(m_overlay_helper.blue_top_face());
 
-      (*rev_iter)->set_subcurve_above(NULL);
+      (*rev_iter)->set_subcurve_above(nullptr);
       sc_above = *rev_iter;
       ++rev_iter;
     }
@@ -484,7 +484,7 @@ after_handle_event(Event* event, Status_line_iterator iter, bool flag)
     if (! curr_sc->has_same_color(sc_above))
       curr_sc->set_subcurve_above(sc_above);
     else {
-      if (sc_above->subcurve_above() != NULL)
+      if (sc_above->subcurve_above() != nullptr)
         curr_sc->set_subcurve_above(sc_above->subcurve_above());
       else
         curr_sc->set_top_face(sc_above);
@@ -771,7 +771,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
       // face. We have to find the identity of this containing blue face.
       Subcurve* sc_above = sc->subcurve_above();
       red_face = red_he->face();
-      blue_face = (sc_above != NULL) ?
+      blue_face = (sc_above != nullptr) ?
         sc_above->blue_halfedge_handle()->face() : sc->blue_top_face();
     }
     else {
@@ -781,7 +781,7 @@ insert_at_vertices(const X_monotone_curve_2& cv,
       // face. We have to find the identity of this containing red face.
       Subcurve* sc_above = sc->subcurve_above();
       blue_face = blue_he->face();
-      red_face = (sc_above != NULL) ?
+      red_face = (sc_above != nullptr) ?
         sc_above->red_halfedge_handle()->face() : sc->red_top_face();
     }
 
@@ -835,7 +835,7 @@ insert_isolated_vertex(const Point_2& pt,
       // sufficient to go at most two steps up.
       // There is nothing above the vertex - use the current red top face.
       Subcurve* sc_above = *iter;
-      if (sc_above == NULL) {
+      if (sc_above == nullptr) {
         red_face = m_overlay_helper.red_top_face();
       }
       else {
@@ -844,7 +844,7 @@ insert_isolated_vertex(const Point_2& pt,
         }
         else {
           sc_above = sc_above->subcurve_above();
-          red_face = (sc_above != NULL) ?
+          red_face = (sc_above != nullptr) ?
             sc_above->red_halfedge_handle()->face() :
             m_overlay_helper.red_top_face();
         }
@@ -871,7 +871,7 @@ insert_isolated_vertex(const Point_2& pt,
       // sufficient to go at most two steps up.
       // If we do not find a blue halfedge, we use the current red top face.
       Subcurve* sc_above = *iter;
-      if (sc_above == NULL) {
+      if (sc_above == nullptr) {
         blue_face = m_overlay_helper.blue_top_face();
       }
       else {
@@ -880,7 +880,7 @@ insert_isolated_vertex(const Point_2& pt,
         }
         else {
           sc_above = sc_above->subcurve_above();
-          blue_face = (sc_above != NULL) ?
+          blue_face = (sc_above != nullptr) ?
             sc_above->blue_halfedge_handle()->face() :
             m_overlay_helper.blue_top_face();
         }
@@ -991,20 +991,20 @@ _create_vertex(Event* event,
       (event->parameter_space_in_y() != ARR_INTERIOR))
   {
     if (!red_handle) {
-      CGAL_assertion(blue_handle != NULL);
+      CGAL_assertion(blue_handle != nullptr);
       // Obtain the red face by looking for a subcurve above.
       const Subcurve* sc_above = sc->subcurve_above();
-      Face_handle_red red_f = (sc_above != NULL) ?
+      Face_handle_red red_f = (sc_above != nullptr) ?
         sc_above->red_halfedge_handle()->face() : sc->red_top_face();
       Handle_info info = std::make_pair(Cell_handle_red(red_f), *blue_handle);
       m_vertices_map[new_v] = info;
       return;
     }
     if (!blue_handle) {
-      CGAL_assertion(red_handle != NULL);
+      CGAL_assertion(red_handle != nullptr);
       // Obtain the blue face by looking for a subcurve above.
       const Subcurve* sc_above = sc->subcurve_above();
-      Face_handle_blue blue_f = (sc_above != NULL) ?
+      Face_handle_blue blue_f = (sc_above != nullptr) ?
         sc_above->blue_halfedge_handle()->face() : sc->blue_top_face();
       Handle_info info = std::make_pair(*red_handle, Cell_handle_blue(blue_f));
       m_vertices_map[new_v] = info;
@@ -1034,10 +1034,10 @@ _create_vertex(Event* event,
     // A blue vertex is located inside a red face. Obtain the red face
     // by looking for a subcurve above.
     const Subcurve* sc_above = sc->subcurve_above();
-    Face_handle_red red_f = (sc_above != NULL) ?
+    Face_handle_red red_f = (sc_above != nullptr) ?
       sc_above->red_halfedge_handle()->face() : sc->red_top_face();
 
-    CGAL_assertion(blue_handle != NULL);
+    CGAL_assertion(blue_handle != nullptr);
     const Vertex_handle_blue& blue_v =
       boost::get<Vertex_handle_blue>(*blue_handle);
     m_overlay_traits->create_vertex(red_f, blue_v, new_v);
@@ -1048,10 +1048,10 @@ _create_vertex(Event* event,
     // A red vertex is located inside a blue face. Obtain the blue face
     // by looking for a subcurve above.
     const Subcurve* sc_above = sc->subcurve_above();
-    Face_handle_blue blue_f = (sc_above != NULL) ?
+    Face_handle_blue blue_f = (sc_above != nullptr) ?
       sc_above->blue_halfedge_handle()->face() : sc->blue_top_face();
 
-    CGAL_assertion(red_handle != NULL);
+    CGAL_assertion(red_handle != nullptr);
     const Vertex_handle_red& red_v =
       boost::get<Vertex_handle_red>(*red_handle);
     m_overlay_traits->create_vertex(red_v, blue_f, new_v);
@@ -1088,7 +1088,7 @@ _create_edge(Subcurve* sc,
     // We have a red edge on a blue face.
     Halfedge_handle_red   red_he = sc->red_halfedge_handle();
     Subcurve* sc_above = sc->subcurve_above();
-    Face_handle_blue blue_f = (sc_above != NULL) ?
+    Face_handle_blue blue_f = (sc_above != nullptr) ?
       sc_above->blue_halfedge_handle()->face() : sc->blue_top_face();
     m_overlay_traits->create_edge(red_he, blue_f, new_he);
   }
@@ -1098,7 +1098,7 @@ _create_edge(Subcurve* sc,
     // We have a blue edge on a red face.
     Halfedge_handle_blue  blue_he = sc->blue_halfedge_handle();
     Subcurve* sc_above = sc->subcurve_above();
-    Face_handle_red red_f = (sc_above != NULL) ?
+    Face_handle_red red_f = (sc_above != nullptr) ?
       sc_above->red_halfedge_handle()->face() : sc->red_top_face();
     m_overlay_traits->create_edge(red_f, blue_he, new_he);
   }

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_overlay_subcurve.h

@@ -94,7 +94,7 @@ protected:
   union {
     const Face_red* red;
     const Face_blue* blue;
-  } m_top_face;         // If m_above is NULL, points the top face in
+  } m_top_face;         // If m_above is nullptr, points the top face in
                         // the arrangement of the opposite color that
                         // contains the subcurve.
 
@@ -102,14 +102,14 @@ public:
   /*! Constructor. */
   Arr_overlay_subcurve() :
     Base(),
-    m_above(NULL)
+    m_above(nullptr)
-  { m_top_face.red = NULL; }
+  { m_top_face.red = nullptr; }
 
   /*! constructor given a curve. */
   Arr_overlay_subcurve(const X_monotone_curve_2& curve) :
     Base(curve),
-    m_above(NULL)
+    m_above(nullptr)
-  { m_top_face.red = NULL; }
+  { m_top_face.red = nullptr; }
 
   /*! Get the subcurve lying above above this subcurve in the status line. */
   Self* subcurve_above() const { return m_above; }
@@ -149,10 +149,10 @@ public:
   /*! Copy the top face from the given subcurve. */
   void set_top_face(const Self* sc)
   {
-    CGAL_precondition(sc->m_above == NULL);
+    CGAL_precondition(sc->m_above == nullptr);
 
     // Mark there is no curve above and copy the face pointer.
-    m_above = NULL;
+    m_above = nullptr;
     m_top_face.red = sc->m_top_face.red;
   }
 };

Arrangement_on_surface_2/include/CGAL/Surface_sweep_2/Arr_overlay_traits_2.h

@@ -314,25 +314,25 @@ public:
     void set_blue_cell(const Optional_cell_blue& cell_blue)
     { m_blue_cell = cell_blue; }
 
-    /*! Obtain the red cell handle or NULL if it doesn't exist. */
+    /*! Obtain the red cell handle or nullptr if it doesn't exist. */
     const Cell_handle_red* red_cell_handle() const
-    { return m_red_cell ? &(*m_red_cell) : NULL; }
+    { return m_red_cell ? &(*m_red_cell) : nullptr; }
 
-    /*! Obtain the blue cell handle or NULL if it doesn't exist. */
+    /*! Obtain the blue cell handle or nullptr if it doesn't exist. */
     const Cell_handle_blue* blue_cell_handle() const
-    { return m_blue_cell ? &(*m_blue_cell) : NULL; }
+    { return m_blue_cell ? &(*m_blue_cell) : nullptr; }
 
-    /*! Obtain the red vertex handle or NULL if it doesn't exist. */
+    /*! Obtain the red vertex handle or nullptr if it doesn't exist. */
     const Vertex_handle_red* red_vertex_handle() const
     {
-      return m_red_cell ? boost::get<Vertex_handle_red>(&(*m_red_cell)) : NULL;
+      return m_red_cell ? boost::get<Vertex_handle_red>(&(*m_red_cell)) : nullptr;
     }
 
-    /*! Obtain the blue vertex handle or NULL if it doesn't exist. */
+    /*! Obtain the blue vertex handle or nullptr if it doesn't exist. */
     const Vertex_handle_blue* blue_vertex_handle() const
     {
       return
-        m_blue_cell ? boost::get<Vertex_handle_blue>(&(*m_blue_cell)) : NULL;
+        m_blue_cell ? boost::get<Vertex_handle_blue>(&(*m_blue_cell)) : nullptr;
     }
   };
 
@@ -437,7 +437,7 @@ public:
       while (oi != oi_end) {
         base_ipt = object_cast<std::pair<Base_point_2, unsigned int> >(&(*oi));
 
-        if (base_ipt != NULL) {
+        if (base_ipt != nullptr) {
           // We have a red-blue intersection point, so we attach the
           // intersecting red and blue halfedges to it.
           Optional_cell_red red_cell;
@@ -464,7 +464,7 @@ public:
         }
         else {
           overlap_xcv = object_cast<Base_x_monotone_curve_2>(&(*oi));
-          CGAL_assertion(overlap_xcv != NULL);
+          CGAL_assertion(overlap_xcv != nullptr);
 
           // We have a red-blue overlap, so we mark the curve accordingly.
           Halfedge_handle_red        red_he;

BGL/doc/BGL/graph_traits.txt

@@ -116,7 +116,7 @@ For convenience, the type `edge_descriptor` is hashable using the functor `CGAL:
 <ul>
 <li> The item class used by `CGAL::Linear_cell_complex_for_combinatorial_map` must have both 0-attributes and 2-attributes enabled.</li>
 
-<li> No dart is 1-free, nor 2-free. Holes in a mesh are represented by using the same convention than for `CGAL::Polyhedron_3` and `CGAL::Surface_mesh`: a dart <code>d</code> belongs to a border if the 2-attribute of <code>beta<2>(d)</code> is NULL.</li>
+<li> No dart is 1-free, nor 2-free. Holes in a mesh are represented by using the same convention than for `CGAL::Polyhedron_3` and `CGAL::Surface_mesh`: a dart <code>d</code> belongs to a border if the 2-attribute of <code>beta<2>(d)</code> is nullptr.</li>
 
 <li> All darts of the linear cell complexes must be associated with a 2-attribute, except darts that represent holes.</li>
 

BGL/include/CGAL/boost/graph/Face_filtered_graph.h

@@ -370,12 +370,12 @@ struct Face_filtered_graph
     {}
 
     Is_simplex_valid()
-      :adapter(NULL)
+      :adapter(nullptr)
     {}
     template<typename Simplex>
     bool operator()(Simplex s)
     {
-      CGAL_assertion(adapter!=NULL);
+      CGAL_assertion(adapter!=nullptr);
       return (adapter->is_in_cc(s));
     }
     const Self* adapter;

BGL/include/CGAL/boost/graph/Graph_with_descriptor_with_graph.h

@@ -44,11 +44,11 @@ public:
   Descriptor descriptor;
 
   Gwdwg_descriptor()
-    : graph(NULL), descriptor()
+    : graph(nullptr), descriptor()
   {}
 
   Gwdwg_descriptor(Descriptor descriptor)
-    : graph(NULL), descriptor(descriptor)
+    : graph(nullptr), descriptor(descriptor)
   {}
 
   Gwdwg_descriptor(Descriptor descriptor, Graph& graph)
@@ -60,7 +60,7 @@ template<typename Graph,typename Descriptor>
 bool operator==(const Gwdwg_descriptor<Graph,Descriptor>& lhs,
                 const Gwdwg_descriptor<Graph,Descriptor>& rhs)
 {
-  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==NULL || lhs.graph==NULL);
+  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==nullptr || lhs.graph==nullptr);
   return lhs.descriptor == rhs.descriptor;
 }
 
@@ -75,7 +75,7 @@ template<typename Graph,typename Descriptor>
 bool operator<(const Gwdwg_descriptor<Graph,Descriptor>& lhs,
                 const Gwdwg_descriptor<Graph,Descriptor>& rhs)
 {
-  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==NULL || lhs.graph==NULL);
+  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==nullptr || lhs.graph==nullptr);
   return lhs.descriptor < rhs.descriptor;
 }
 
@@ -83,7 +83,7 @@ template<typename Graph,typename Descriptor>
 bool operator>(const Gwdwg_descriptor<Graph,Descriptor>& lhs,
                 const Gwdwg_descriptor<Graph,Descriptor>& rhs)
 {
-  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==NULL || lhs.graph==NULL);
+  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==nullptr || lhs.graph==nullptr);
   return lhs.descriptor > rhs.descriptor;
 }
 
@@ -91,7 +91,7 @@ template<typename Graph,typename Descriptor>
 bool operator<=(const Gwdwg_descriptor<Graph,Descriptor>& lhs,
                 const Gwdwg_descriptor<Graph,Descriptor>& rhs)
 {
-  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==NULL || lhs.graph==NULL);
+  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==nullptr || lhs.graph==nullptr);
   return lhs.descriptor <= rhs.descriptor;
 }
 
@@ -99,7 +99,7 @@ template<typename Graph,typename Descriptor>
 bool operator>=(const Gwdwg_descriptor<Graph,Descriptor>& lhs,
                 const Gwdwg_descriptor<Graph,Descriptor>& rhs)
 {
-  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==NULL || lhs.graph==NULL);
+  CGAL_assertion( lhs.graph == rhs.graph || rhs.graph==nullptr || lhs.graph==nullptr);
   return lhs.descriptor >= rhs.descriptor;
 }
 
@@ -142,7 +142,7 @@ struct Graph_with_descriptor_with_graph
   typedef Gwdwg_descriptor<Graph, typename gt::face_descriptor> face_descriptor;
 
   Graph_with_descriptor_with_graph()
-    : graph(NULL)
+    : graph(nullptr)
   {}
 
   Graph_with_descriptor_with_graph(Graph& graph)
@@ -156,7 +156,7 @@ struct Descriptor2Descriptor: public CGAL::cpp98::unary_function<Graph_descripto
 {
 
   Descriptor2Descriptor()
-    : graph(NULL)
+    : graph(nullptr)
   {}
 
   Descriptor2Descriptor(Graph& graph)
@@ -166,7 +166,7 @@ struct Descriptor2Descriptor: public CGAL::cpp98::unary_function<Graph_descripto
   Descriptor
   operator()(Graph_descriptor gd) const
   {
-    CGAL_assertion(graph!=NULL);
+    CGAL_assertion(graph!=nullptr);
     return Descriptor(gd,*graph);
   }
 
@@ -716,7 +716,7 @@ struct Graph_with_descriptor_with_graph_property_map {
   PM pm;
 
   Graph_with_descriptor_with_graph_property_map()
-    : graph(NULL)
+    : graph(nullptr)
   {}
 
   Graph_with_descriptor_with_graph_property_map(const Graph& graph, const PM& pm)
@@ -728,7 +728,7 @@ struct Graph_with_descriptor_with_graph_property_map {
   reference
   get(const Graph_with_descriptor_with_graph_property_map<Graph,PM>& gpm, const Descriptor& d)
   {
-    CGAL_assertion(gpm.graph!=NULL);
+    CGAL_assertion(gpm.graph!=nullptr);
     CGAL_assertion(d.graph == gpm.graph);
     return get(gpm.pm, d.descriptor);
   }
@@ -738,7 +738,7 @@ struct Graph_with_descriptor_with_graph_property_map {
   void
   put(const Graph_with_descriptor_with_graph_property_map<Graph,PM>& gpm, const Descriptor& d,   const value_type& v)
   {
-    CGAL_assertion(gpm.graph!=NULL);
+    CGAL_assertion(gpm.graph!=nullptr);
     CGAL_assertion(d.graph == gpm.graph);
     put(gpm.pm, d.descriptor, v);
   }
@@ -762,7 +762,7 @@ struct Graph_with_descriptor_with_graph_property_map<Graph, PM, boost::lvalue_pr
   }
 
   Graph_with_descriptor_with_graph_property_map()
-    : graph(NULL)
+    : graph(nullptr)
   {}
 
   Graph_with_descriptor_with_graph_property_map(const Graph& graph, const PM& pm)
@@ -774,7 +774,7 @@ struct Graph_with_descriptor_with_graph_property_map<Graph, PM, boost::lvalue_pr
   reference
   get(const Graph_with_descriptor_with_graph_property_map<Graph,PM>& gpm, const Descriptor& d)
   {
-    CGAL_assertion(gpm.graph!=NULL);
+    CGAL_assertion(gpm.graph!=nullptr);
     CGAL_assertion(d.graph == gpm.graph);
     return get(gpm.pm, d.descriptor);
   }
@@ -784,7 +784,7 @@ struct Graph_with_descriptor_with_graph_property_map<Graph, PM, boost::lvalue_pr
   void
   put(const Graph_with_descriptor_with_graph_property_map<Graph,PM>& gpm, const Descriptor& d,   const value_type& v)
   {
-    CGAL_assertion(gpm.graph!=NULL);
+    CGAL_assertion(gpm.graph!=nullptr);
     CGAL_assertion(d.graph == gpm.graph);
     put(gpm.pm, d.descriptor, v);
   }

BGL/include/CGAL/boost/graph/METIS/partition_dual_graph.h

@@ -97,11 +97,11 @@ void partition_dual_graph(const TriangleMesh& tm,
 
   // partition info for the nodes
   idx_t* npart = (idx_t*) calloc(num_vertices(tm), sizeof(idx_t));
-  CGAL_assertion(npart != NULL);
+  CGAL_assertion(npart != nullptr);
 
   // partition info for the elements
   idx_t* epart = (idx_t*) calloc(num_faces(tm), sizeof(idx_t));
-  CGAL_assertion(epart != NULL);
+  CGAL_assertion(epart != nullptr);
 
   // do not support Fortran-style arrays
   CGAL_assertion((*options)[METIS_OPTION_NUMBERING] == -1 || // default initialization is '-1'
@@ -109,9 +109,9 @@ void partition_dual_graph(const TriangleMesh& tm,
 
   CGAL_assertion_code(int ret =)
     METIS_PartMeshDual(&ne, &nn, eptr, eind,
-                       NULL /* elements weights*/, NULL /*elements sizes*/,
+                       nullptr /* elements weights*/, nullptr /*elements sizes*/,
                        &ncommon, &nparts,
-                       NULL /* partitions weights */,
+                       nullptr /* partitions weights */,
                        *options,
                        &objval, epart, npart);
 

BGL/include/CGAL/boost/graph/METIS/partition_graph.h

@@ -129,11 +129,11 @@ void partition_graph(const TriangleMesh& tm,
 
   // partition info for the nodes
   idx_t* npart = (idx_t*) calloc(num_vertices(tm), sizeof(idx_t));
-  CGAL_assertion(npart != NULL);
+  CGAL_assertion(npart != nullptr);
 
   // partition info for the elements
   idx_t* epart = (idx_t*) calloc(num_faces(tm), sizeof(idx_t));
-  CGAL_assertion(epart != NULL);
+  CGAL_assertion(epart != nullptr);
 
   // do not support Fortran-style arrays
   CGAL_assertion((*options)[METIS_OPTION_NUMBERING] == -1 || // default initialization is '-1'
@@ -141,9 +141,9 @@ void partition_graph(const TriangleMesh& tm,
 
   CGAL_assertion_code(int ret =)
     METIS_PartMeshNodal(&ne, &nn, eptr, eind,
-                        NULL /* nodes weights */, NULL /* nodes sizes */,
+                        nullptr /* nodes weights */, nullptr /* nodes sizes */,
                         &nparts,
-                        NULL /* partitions weights */,
+                        nullptr /* partitions weights */,
                         *options,
                         &objval, epart, npart);