获取错误代码

    DWORD dwError = GetLastError();
    DWORD systemLocale = MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL);
    HLOCAL hlocal = NULL;   // Buffer that gets the error message string
    BOOL fOk = FormatMessage(
         FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS |
         FORMAT_MESSAGE_ALLOCATE_BUFFER, 
         NULL, dwError, systemLocale, 
         (PTSTR) &hlocal, 0, NULL);

    if (!fOk)
    {
        // Is it a network-related error?
        HMODULE hDll = LoadLibraryEx(TEXT("netmsg.dll"), NULL, 
            DONT_RESOLVE_DLL_REFERENCES);
        if (hDll != NULL)
        {
            fOk = FormatMessage(
                FORMAT_MESSAGE_FROM_HMODULE | FORMAT_MESSAGE_IGNORE_INSERTS |
                FORMAT_MESSAGE_ALLOCATE_BUFFER,
                hDll, dwError, systemLocale,
                (PTSTR) &hlocal, 0, NULL);
            FreeLibrary(hDll);
        }
    }

    if (fOk && (hlocal != NULL))
    {
        AfxMessageBox((PCTSTR) LocalLock(hlocal));
        LocalFree(hlocal);
    }