Why can I not set "Game Window Class" as my class name?

Question

I'm wondering why I cannot set the name. This is the error:

It doesn't even let me assign a char.

#include <windows.h>

LRESULT CALLBACK window_callback(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

int WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nShowCmd)
{
    //create window class
    WNDCLASS window_class = {};
    window_class.style = CS_HREDRAW | CS_VREDRAW;
    window_class.lpszClassName = "Game Window Class";
    window_class.lpfnWndProc = window_callback;//callback
    
    //Register class

    //Create window
}

Answer 1

WNDCLASS::lpszClassName is an LPCTSTR pointer, ie a const TCHAR* pointer. TCHAR maps to wchar_t when UNICODE is defined, otherwise it maps to char instead.

You are compiling your project with UNICODE defined, because lpszClassName is expecting a wide const wchar_t* pointer to a Unicode string, but you are giving it a (decayed) narrow const char* pointer to an ANSI string literal instead, hence the error.

You can either:

• undefine UNICODE in your project settings.

• prefix the string literal with L to make it a Unicode string:

  window_class.lpszClassName = L"Game Window Class";

• wrap the string literal in the TEXT() macro:

  window_class.lpszClassName = TEXT("Game Window Class");