最简单的不用定义那么多C语言变量：
HWND hwnd=NULL;
int iRet;
hwnd=FindWindow(NULL,"WinCC-运行系统 - ");

if (strcmp(GetTagChar("user"),GetTagChar("pass"))==0)
{
SetTagBit("success",1);
iRet=MessageBox(hwnd,"登陆系统成功！","对话框",MB_YESNOMB_ICONQUESTIONMB_APPLMODAL);
}
else
{
SetTagBit("success",0);
iRet=MessageBox(hwnd,"登陆系统失败！","对话框",MB_YESNOMB_ICONQUESTIONMB_APPLMODAL);
}