Question

The Code

window.h

typedef struct
{
    WNDCLASS* wc;
    HWND hwnd;
    WNDPROC proc;
} PRO_Window;

PRO_Window* PRO_WindowCreate(int width, int height, const char* title);

window.c
_{I don’t think this is important though…}

PRO_Window* PRO_WindowCreate(int width, int height, const char* title) { /* code */ }

main.c

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR CmdLine, int nCmdShow)
{
    PRO_Window* win = PRO_WindowCreate( 300, 300, "STATIC");
    return 0;
}

The Error

GCC

main.o:main.c|| undefined reference to `PRO_WindowCreate(int, int, char const*)'|

<sub>* Reduced it to SSCCE
* I am using the windows api</sub>

Answer 1

The error with Boarland-C compiler seems to be because of the declaration of wc after the wnd->proc = NULL;. Try to move declaration above initialization statement…