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[BomBielFil <>]

Hi
someone could tell me how compile (g++ command) the example of Qt_widget in cgal manual ??
the example is:
#include <CGAL/basic.h>

#ifndef CGAL_USE_QT
#include <iostream>

int main(int, char*){

  std::cout << "Sorry, this demo needs QT..." << std::endl; return 0;}
#else
#include <CGAL/Cartesian.h>

#include <CGAL/IO/Qt_widget.h>

#include <qapplication.h>

typedef CGAL::Cartesian<int> Rep;

typedef CGAL::Point_2<Rep> Point_2;

typedef CGAL::Segment_2<Rep> Segment;

int main( int argc, char **argv )

{
  QApplication app( argc, argv );
  CGAL::Qt_widget *w = new CGAL::Qt_widget();

  app.setMainWidget( w );
  w->resize(600, 600);
  w->set_window(0, 600, 0, 600);
  w->show();
  w->lock();
  *w << CGAL::BackgroundColor(CGAL::ORANGE) << CGAL::RED;
  *w << Segment(Point_2(100,100), Point_2(400,400));

  w->unlock();
  return app.exec();
}
#endif
my first error line is : "undefined reference to 'QApplication::QApplication(int&, char**)"

It's the first time that I use this package
Thanks
Best Regard
-Bombielfil-