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The title’s kind of a misnomer. This post is really to help me remember how to get a human-readable string from a Windows error code… I’m finally tired of always having to look it up . However, my current situation revolves around determining why a DLL (or *.so on Linux) failed to load, so that’s why this post it titled the way it is.

I like to disable the annoying default dialog that pops up in Windows when a library fails to load.

SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX | SEM_NOALIGNMENTFAULTEXCEPT | SEM_NOOPENFILEERRORBOX);

Now, here’s the code to get a user friendly text string:

#ifdef WIN32
    LPVOID pStr = 0;
    DWORD_PTR args[1] = { (DWORD_PTR)pFilename };
    FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_ARGUMENT_ARRAY,
        NULL,
        GetLastError(),
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR)&pStr,
        0,
        (va_list*)args);

    /* Do something with the string pStr here */

    LocalFree(pStr);
#else
    /* Call dlerror() and do something with the string */
#endif