Detect 32-bit or 64-bit of Windows

The function to call is IsWow64Process or IsWow64Process2. It tells your 32-bit application if it is running on a 64 bit Windows.

If the program is compiled for 64 bits, it will already know.

If your code is 64-bit and running, then Windows is 64-bit - nothing to check. If your process is 32-bit call IsWow64Process() - 32-bit processes run in WOW64 on 64-bit Windows and without WOW64 otherwise.

bool getWindowsBit(bool & isWindows64bit){#if _WIN64    isWindows64bit =  true;    return true;#elif _WIN32    BOOL isWow64 = FALSE;    //IsWow64Process is not available on all supported versions of Windows.    //Use GetModuleHandle to get a handle to the DLL that contains the function    //and GetProcAddress to get a pointer to the function if available.    LPFN_ISWOW64PROCESS fnIsWow64Process  = (LPFN_ISWOW64PROCESS) GetProcAddress(GetModuleHandle(TEXT("kernel32")),"IsWow64Process");    if(fnIsWow64Process)    {        if (!fnIsWow64Process(GetCurrentProcess(), &isWow64))            return false;        if(isWow64)            isWindows64bit =  true;        else            isWindows64bit =  false;        return true;    }    else        return false;#else    assert(0);    return false;#endif}