windows and dev-cpp

#include in cgfxopengl.h

Have you doe #include in cgfxopengl.cpp or a header that is included by it?

i included windows.h in cgfxopengl.h and it works now, but could you maybe tell me why ? (i included windows.h in cgfxopengl.cpp).

Thanks very much.

The compiler only deals with one .cpp file at a time. It forgets everything it saw in any other cpp file. So if you include windows.h in winmain.cpp, the compiler compiles it and reads windows.h where it finds the definitons of PostQuitMessage and so on.
Then it compiles cgfxopengl.cpp, and it comes across PostQuitMessage(). However, it doesn't know what this is (it hasn't seen it declared before because you haven't included windows.h, and it doesn't know about winmain.cpp), so it gives you an error.

The compiler only compiles one .cpp file at a time. The linker puts all the parts together into one executable file.

Again, thanks very much.

Peter