improve example

Surface_mesh/examples/Surface_mesh/sm_iterators_and_circulators.cpp

@@ -39,9 +39,34 @@ int main()
 
   { 
     std::cout << "all vertices " << std::endl;
+
+    // The vertex iterator type is a nested type of the Vertex_range
+    Mesh::Vertex_range::iterator  vb, ve;
+
+    Mesh::Vertex_range r = m.vertices();
+    // The iterators can be accessed through the C++ range API
+    vb = r.begin(); 
+    ve = r.end();
+    // or the boost Range API
+    vb = boost::begin(r);
+    ve = boost::end(r);
+
+    // or with boost::tie, as the CGAL range derives from std::pair
+    for(boost::tie(vb, ve) = m.vertices(); vb != ve; ++vb){
+            std::cout << *vb << std::endl;
+    }
+    
+    // Instead of the classical for loop one can use
+    // the boost macro for a range
     BOOST_FOREACH(vertex_descriptor vd, m.vertices()){
       std::cout << vd << std::endl;
     }
+
+    // or the C+11 for loop. Note that there is a ':' and not a ',' as in BOOST_FOREACH 
+    for(vertex_descriptor vd : m.vertices()){
+      std::cout << vd << std::endl;
+    }
+    
   }
 
   {