程序为网络程序，应使用socket编程，服务器要实现对每一个访问的客户机发送一个欢迎消息，可选用select（）函数实现I/O多路复用，服务器通过socket相关函数来建立TCP连接，监听每一个访问的客户端，当有客户端向服务器发起连接时，将客户端文件描述符加入监听描述符集，客户端向服务器发送信息，同时也收到服务器发来的”Hello,Welcome Client！”。

本题需要写两个程序，分别是“server.c”和“client.c”。前者主要是在服务器端执行并等待客户端访问操作然后发欢迎信息，后者主要是向主机发送访问命令并接收服务器发来的欢迎信息。-Procedures for network programs, you should use socket programming, server to achieve for each visit to a client sends a welcome message, the choice of　() function to achieve I/O multiplexers, server through socket correlation function to establish a TCP connection, monitor each client visit, when a client initiates a connection to the server, the client file descr iptor join listening descr iptor set, the client sends a message to the server, and also received a server sent　Hello, Welcome Client !.　

That the need to write two programs, namely　server.c　and　client.c . The former is mainly　d and waiting for clients to access operations and then send a welcome message on the server side, which is mainly access to the host sends commands and receives the welcome message sent　the server.