Don't rely on the implicit conversion QString -> const char*.

Don't do it on temporaries.
stddef.h missing in qt3 headers.

Alpha_shapes_2/demo/Alpha_shapes_2/alpha_shapes_2.cpp

@@ -403,7 +403,7 @@ private slots:
       QFileDialog::getSaveFileName( "triangulation.cgal",
 				    "Cgal files (*.cgal)", this );
     if ( !fileName.isNull() ) {                 // got a file name
-      std::ofstream out(fileName);
+      std::ofstream out(fileName.ascii());
       CGAL::set_ascii_mode(out);
       out << tr1 << std::endl;
     }
@@ -418,7 +418,7 @@ private slots:
     tr1.clear();
     A.clear();
     L.clear();
-    std::ifstream in(s);
+    std::ifstream in(s.ascii());
     CGAL::set_ascii_mode(in);
     in >> tr1;
     Vertex_iterator it = tr1.vertices_begin();

Arrangement_on_surface_2/demo/Arrangement_on_surface_2/MyWindow_files.cpp

@@ -192,7 +192,7 @@ void MyWindow::fileOpenPm()
     statusBar()->message( "File Open abandoned", 2000 );
 	return;
   }
-  std::ifstream inputFile(filename);
+  std::ifstream inputFile(filename.ascii());
   // Creates an ifstream object named inputFile
   if (! inputFile.is_open()) // Always test file open
   {
@@ -253,7 +253,7 @@ void MyWindow::fileOpenPm()
  */
 void MyWindow::load( const QString& filename , bool clear_flag )
 {
-  std::ifstream inputFile(filename);
+  std::ifstream inputFile(filename.ascii());
   // Creates an ofstream object named inputFile
   if (! inputFile.is_open()) // Always test file open
   {
@@ -603,7 +603,7 @@ void MyWindow::fileSave()
     return;
   }
 
-  std::ofstream outFile(m_filename);
+  std::ofstream outFile(m_filename.ascii());
   // Creates an ofstream object named outFile
   if (! outFile.is_open()) // Always test file open
   {

Arrangement_on_surface_2/demo/Arrangement_on_surface_2/demo_tab.h

@@ -27,6 +27,7 @@
  *  the differences is in the traits classes.
  */
 
+#include <stddef.h>
 #include <math.h>
 #include <limits>
 

Boolean_set_operations_2/demo/Boolean_set_operations_2/boolean_operations_2.cpp

@@ -512,7 +512,7 @@ void MyWindow::open_dxf_file()
     return;
   file_name=s;
 
-  std::ifstream in_file(s);
+  std::ifstream in_file(s.ascii());
   if (!in_file.is_open())
     {
       QMessageBox::warning( widget,"Open","Can't open file");
@@ -606,7 +606,7 @@ void MyWindow::open_linear_polygon_file()
     return;
   file_name=s;
 
-  std::ifstream in_file(s);
+  std::ifstream in_file(s.ascii());
   if (!in_file.is_open())
     {
       QMessageBox::warning( widget,"Open","Can't open file");

Nef_2/demo/Nef_2/nef_2.cpp

@@ -307,7 +307,7 @@ public slots:
 		    "CGAL files (*.cgal)", this ) );
     if ( s.isEmpty() )
       return;
-    std::ifstream in(s);
+    std::ifstream in(s.ascii());
     CGAL::set_ascii_mode(in);
     Nef_polyhedron N_temp(Nef_polyhedron::EMPTY);
     Nef_visible2 = N_temp;
@@ -327,7 +327,7 @@ public slots:
                        "Cgal files (*.cgal)", this );
     if ( !fileName.isNull() ) {
       // got a file name
-      std::ofstream out(fileName);
+      std::ofstream out(fileName.ascii());
       CGAL::set_ascii_mode(out);
       out << Nef_visible << std::endl;
     }
@@ -338,7 +338,7 @@ public slots:
 		    "CGAL files (*.cgal)", this ) );
     if ( s.isEmpty() )
       return;
-    std::ifstream in(s);
+    std::ifstream in(s.ascii());
     CGAL::set_ascii_mode(in);
 
     Polygon_2_double poly;

Snap_rounding_2/demo/Snap_rounding_2/snap_rounding_2.cpp

@@ -238,7 +238,7 @@ public slots:
     if ( s.isEmpty() )
         return;
     seg_list.clear();
-    std::ifstream in(s);
+    std::ifstream in(s.ascii());
     CGAL::set_ascii_mode(in);
     int number_of_segments = 0,i;
     CGAL::Segment_data<Rep> seg;
@@ -286,7 +286,7 @@ public slots:
                                   "Cgal files (*.cgal)", this );
     if ( !fileName.isNull() ) {
       // got a file name
-      std::ofstream out(fileName);
+      std::ofstream out(fileName.ascii());
       CGAL::set_ascii_mode(out);
       out << seg_list.size() << std::endl << prec << std::endl;
       std::list<Segment_2>::const_iterator it = seg_list.begin();

Straight_skeleton_2/demo/Straight_skeleton_2/straight_skeleton_2.cpp

@@ -383,7 +383,7 @@ private slots:
 
         if ( !fileName.isNull() )
         {
-          std::ofstream out(fileName);
+          std::ofstream out(fileName.ascii());
 
           CGAL::set_ascii_mode(out);
 
@@ -410,7 +410,8 @@ private slots:
     bool auto_create_offsets = true ;
     offsets.clear() ;
 
-    std::ifstream offsets_file(s + QString(".oft") );
+    QString soft = s + QString(".oft");
+    std::ifstream offsets_file(soft.ascii());
     if ( offsets_file )
     {
       CGAL::set_ascii_mode(offsets_file);
@@ -424,7 +425,7 @@ private slots:
       auto_create_offsets = false ;
     }
 
-    std::ifstream in(s);
+    std::ifstream in(s.ascii());
     if ( in )
     {
       CGAL::set_ascii_mode(in);

Stream_lines_2/demo/Stream_lines_2/streamlines.cpp

@@ -134,7 +134,7 @@ class Placement : public QObject
     void load( const QString & s )
     {
       runge_kutta_integrator = new Runge_kutta_integrator(integrating_);
-      std::ifstream infile(s, std::ios::in);
+      std::ifstream infile(s.ascii(), std::ios::in);
       double iXSize, iYSize;
       iXSize = iYSize = 512;
       unsigned int x_samples, y_samples;
@@ -352,14 +352,14 @@ class MyWidget : public QGLWidget
     QString savedepsfile(){
       QString s = QFileDialog::getSaveFileName( ".",
           "Encapsulated PostScript files (*.eps)", this, "save file dialog", "Save file to" );
-      std::ofstream fw(s,std::ios::out);
+      std::ofstream fw(s.ascii(),std::ios::out);
       p.Stream_lines->print_stream_lines_eps(fw);
       return s;
     }
     QString savedstlfile(){
       QString s = QFileDialog::getSaveFileName( ".",
           "STreamLine files (*.stl)", this, "save file dialog", "Save file to" );
-      std::ofstream fw(s,std::ios::out);
+      std::ofstream fw(s.ascii(),std::ios::out);
       p.Stream_lines->print_stream_lines(fw);
       return s;
     }