is-wine.c

#include <windows.h>
#include <stdio.h>

int main(void)
{
    static const char* (CDECL *pwine_get_version)(void);
    HMODULE hntdll = GetModuleHandle("ntdll.dll");
    if(!hntdll) {
        puts("Running on Windows 9x.");
        return 1;
    }

    pwine_get_version = (void *)GetProcAddress(hntdll, "wine_get_version");

    if(pwine_get_version)
        printf("Running on Wine %s\n", pwine_get_version());
    else
        puts("Running on Windows NT.");

    return 0;
}