VC

// Elevate the process if it is not run as administrator.
if (!fIsRunAsAdmin)
{
    wchar_t szPath[MAX_PATH];
    if (GetModuleFileName(NULL, szPath, ARRAYSIZE(szPath)))
    {
        // Launch itself as administrator.
        SHELLEXECUTEINFO sei = { sizeof(sei) };
        sei.lpVerb = L"runas";
        sei.lpFile = szPath;
        sei.hwnd = hWnd;
        sei.nShow = SW_NORMAL;

        if (!ShellExecuteEx(&sei))
        {
            DWORD dwError = GetLastError();
            if (dwError == ERROR_CANCELLED)
            {
                 // The user refused the elevation.
                 // Do nothing ...
            }
        }
        else
        {
            EndDialog(hWnd, TRUE);  // Quit itself
        }
    }
}