请教epoll_wait返回的poll_events中的变量为什么为0

请问epoll_wait返回的poll_events中的变量为什么为0
使用epoll_ctl(epollHandle, EPOLL_CTL_ADD, g_hWatchSocket, &ev)设置了g_hWatchSocket对应的ev，
但是在epoll_wait之后， poll_events[i].data.fd;的值为0，

此时使用recvfrom(g_hWatchSocket, (s8 *)pBuf, dwBufLen, 0 , NULL, NULL);还是可以收到包的

C/C++ code

    u32  dwBufLen = 2048;    u8  *pBuf     = new u8[dwBufLen+1];              g_hWatchSocket = socket(AF_INET, SOCK_DGRAM, 0);            SOCKADDR_IN addr;    memset(&addr, 0, sizeof(SOCKADDR_IN));    addr.sin_family      = AF_INET;     addr.sin_addr.s_addr = 0;    addr.sin_port        = htons(2500);            bind(g_hWatchSocket, (sockaddr *)&addr, sizeof(SOCKADDR_IN)))    SetNonBlocking(g_hWatchSocket);    struct epoll_event ev, poll_events[100];    ev.data.fd  = g_hWatchSocket;    ev.events   = EPOLLIN|EPOLLET;        int epollHandle = epoll_create(100);    int ret = epoll_ctl(epollHandle, EPOLL_CTL_ADD, g_hWatchSocket, &ev);            while(1)    {        nEventNum = epoll_wait(epollHandle, poll_events, 100, 800);        for(int i=0; i < nEventNum; i++)        {                       [color=#FF0000]为什么这里得到的sockfd是0呢？？？？[/color]             sockfd = poll_events[i].data.fd;                    //重新设置g_hWatchSocket的监控类型                ev.data.fd  = g_hWatchSocket;                ev.events   = EPOLLIN | EPOLLET;                epoll_ctl(epollHandle, EPOLL_CTL_MOD, g_hWatchSocket, &ev);            }        }//for(int i=0;i<nEventNum;i++)    }//while(1)