HWND GetHwndByPid(DWORD dwProcessID) 
{ 
    HWND h = GetTopWindow(0); 
    HWND retHwnd = NULL;
    while ( h )  
    { 
        DWORD pid = 0; 
        DWORD dwTheardId = GetWindowThreadProcessId( h,&pid);  
        if (dwTheardId != 0)
        { 
            if ( pid == dwProcessID/*your process id*/ )         
            {
                retHwnd = h;    //会有多个相等值
                //    /*
                char buf[MAX_PATH] = {0};
                sprintf(buf,"%0x",h);
                MessageBox(NULL,buf,"提示",MB_OK);
                //    */
            }
        }
        h  = GetNextWindow(h,GW_HWNDNEXT);
    }
    return retHwnd;
}