linux Socket编程入门

以前已经接触Windows下的Socket编程，最近也尝试着再linux下使用Socket编程，下面是在网上找的例子(已经测试过)
 tcp_server.c:
#include <stdio.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <time.h>
#define SERVER_PORT 20000
#define LENGTH_OF_LISTEN_QUEUE 10
#define BUFFER_SIZE 255
#define WELCOME_MESSAGE "welcome to connect the server"
int main(int argc, char **argv)
{
 int servfd,clifd;
 struct sockaddr_in servaddr,cliaddr;
 if((servfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
 {
  printf("create socket error!\n");
  exit(1);
 }
 bzero(&servaddr, sizeof(servaddr));
 servaddr.sin_family = AF_INET;
 servaddr.sin_port = htons(SERVER_PORT);
 servaddr.sin_addr.s_addr = htons(INADDR_ANY);
 
 if(bind(servfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)
 {
  printf ("bind to port %d failure!\n",SERVER_PORT);
  exit(1);
 }
 
 if(listen(servfd, LENGTH_OF_LISTEN_QUEUE) < 0)
 {
  printf("call listen failure!\n");
  exit(1);
 }
 while(1)
 {
  char buf[BUFFER_SIZE];
  long timestamp;
  socklen_t length = sizeof(cliaddr);
  clifd = accept(servfd, (struct sockaddr*)&cliaddr, &length);
  if(clifd < 0)
  {
   printf("error comes when call accept!\n");
   break;
  }
  strcpy(buf,WELCOME_MESSAGE);
  printf("from client, IP:%s, Port:%d\n", inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port));
  timestamp = time(NULL);
  strcat(buf, "timestamp in server:");
  strcat(buf, ctime(&timestamp));
  send(clifd, buf, BUFFER_SIZE, 0);
  close(clifd);
 }
 close(servfd);
 return 0;
}
tcp_clie