Using Visual C++ Express, I created an empty win32 project (not console) and created the following as main.cpp:

#include <windows.h>

int main()
{
  return 0;
}

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
  return main();
}

Google didn't help in this case. Needless to say, neither did MSDN. This error occurs with both 2005 and 2008 versions.

Roy, I'll dumb it down for you. The following code also produces a C2731:

#include <windows.h>

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
  return 0;
}

It's not that hard to make a GUI app in Win32. Even easier with .NET WinForms.

I found the problem... I was using LPTSTR instead of LPSTR.

The reason I have a main() method called by WinMain is because I'm making a "magic main" system similar to that of Allegro, except simplified for my purposes. I'm actually using it in Ogre and Irrlicht, both of which I'm currently evaluating.

Hey, profit isn't dumb!

You don't need winmain. You can just set SubSystem to Windows in msvc. Then you have to set the entry point to mainCRTStartup. Both are in the linker setting in project properties.

I happened across this from a thread on the cplusplus.com forums :

I don't know if that's accurate or not, but maybe it has something to do with it.

Thank god for .NET anyway, if only so we don't have to deal with winapi calls anymore.