compiler errors - invalid conversion from 'QAbstractOpenGLFunctions*' to 'QOpenGLFunctions_4_3_Core*' in Qt5.1&OpenGL -

i'm learning opengl referencing kdab's article part one. rather new , helpful. however, compile error trying code on page.

there 3 files in qt project: main.cpp, window.cpp , window.h.

window.h:

#ifndef window_h #define window_h  #include <qwindow> #include <qsurfaceformat> #include <qopenglcontext> #include <qopenglfunctions_4_3_core>  class window : public qwindow {     q_object public:     window(qscreen* screen);  signals: private:     qopenglcontext *m_context;     qopenglfunctions_4_3_core* m_funcs; };  #endif // window_h 

window.cpp:

#include "window.h"      window::window(qscreen* screen) :         qwindow(screen)     {         setsurfacetype(openglsurface);          qsurfaceformat format;         format.setdepthbuffersize(24);         format.setmajorversion(4);         format.setminorversion(3);         format.setsamples(4);         format.setprofile(qsurfaceformat::coreprofile);         setformat(format);         create();          m_context = new qopenglcontext;         m_context->setformat(format);         m_context->create();          // make context current on window         m_context->makecurrent( );          // obtain functions object , resolve entry points         // m_funcs declared as: qopenglfunctions_4_3_core* m_funcs         m_funcs = m_context->versionfunctions();         if ( !m_funcs ) {             qwarning( "could not obtain opengl versions object" );             exit( 1 );         }         m_funcs->initializeopenglfunctions();     //    m_funcs->glvertexattribdivisor();     } 

main.cpp:

#include <qcoreapplication> #include <qglwidget>  int main(int argc, char *argv[]) {      qcoreapplication app(argc, argv);     return app.exec(); } 

error: invalid conversion 'qabstractopenglfunctions*' 'qopenglfunctions_4_3_core*' [-fpermissive]

i found solution in qt's document. statement should

m_funcs = m_context->versionfunctions<qopenglfunctions_4_3_core>(); 

then error eliminated.