一个select接收socket数据的例子

cout << "Starting Server...!" << endl; 
    fd_set fdSocket;        // 所有可用套节字集合
    FD_ZERO(&fdSocket);
    FD_SET(m_sockfd, &fdSocket);
    while(TRUE)
    ...{
        // 2）将fdSocket集合的一个拷贝fdRead传递给select函数，
        // 当有事件发生时，select函数移除fdRead集合中没有未决I/O操作的套节字句柄，然后返回。
        fd_set fdRead = fdSocket;
        if (::select(0, &fdRead, NULL, NULL, NULL) <= 0)
        ...{
            cout << " Failed select()" << endl;
            break;
        } 
        // 3）通过将原来fdSocket集合与select处理过的fdRead集合比较，
        // 确定都有哪些套节字有未决I/O，并进一步处理这些I/O。
        for(int i=0; i<(int)fdSocket.fd_count; i++)
        ...{
            if(!FD_ISSET(fdSocket.fd_array[i], &fdRead))
                continue; 
            if(fdSocket.fd_array[i] == m_sockfd)        // （1）监听套节字接收到新连接
            ...{
                if(fdSocket.fd_count < FD_SETSIZE)
                ...{
                    sockaddr_in addrRemote;
                    int nAddrLen = sizeof(addrRemote);
                    SOCKET sNew = ::accept(m_sockfd, (SOCKADDR*)&addrRemote, &nAddrLen);
                    FD_SET(sNew, &fdSocket);
                    cout <<  "接收到连接(" << ::inet_ntoa(addrRemote.sin_addr) << ")" << endl; 
                }
                else
                ...{
                    cout << " Too much connections!" << endl; 
                    continue;
                }
            }
            else
            ...{
                memset(m_recvBuf, 0x00, sizeof(m_recvBuf)/sizeof(m_recvBuf[0])); 
                if(::recv(fdSocket.fd_array[i], (char *)m_recvBuf, 
                sizeof(m_recvBuf)/sizeof(m_recvBuf[0]), 0) > 0)                        // （2）可读
                    cout << "接收到数据：" << m_recvBuf << endl; 
                else                                // （3）连接关闭、重启或者中断
                ...{
                    ::closesocket(fdSocket.fd_array[i]);            
                    FD_CLR(fdSocket.fd_array[i], &fdSocket);
                }
            }
        }
    }