17.5.2 客户端程序

#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>        /*包含头文件。*/

#define PORT 5678         /*定义远程端口。*/
#define REMOTE_IP "127.0.0.1"      /*定义远程IP。*/

int   main(int argc,char *argv[])
{ 
int s ;           /*定义相关变量。*/
struct sockaddr_in addr ;
char mybuffer[256];

   if( (s=socket(AF_INET,SOCK_STREAM,0))<0 )  /*新建一个socket。*/
{
perror("socket");
exit(1);
}
else
{
printf("socket created .\n");
printf("socked id: %d \n",s);
}

   bzero(&addr,sizeof(addr));      /*设置addr。*/
addr.sin_family =AF_INET;
addr.sin_port=htons(PORT);
addr.sin_addr.s_addr=inet_addr(REMOTE_IP);

   if(connect(s,&addr,sizeof(addr))<0)    /*连接远程服务器。*/
{
perror("connect");
exit(1);
}
else
{
    printf("connected ok!\n");
    printf("remote ip:%s\n",REMOTE_IP);
    printf("remote port:%d\n",PORT);
}

   recv(s ,mybuffer,sizeof(mybuffer),0);   /*接收服务器发送的信息。*/
printf("%s\n",mybuffer);       /*输出信息。*/

   while(1)           /*进入一个循环。*/
{
bzero(mybuffer,sizeof(mybuffer));    /*清空mybuffer字符串。*/
read(STDIN_FILENO,mybuffer,sizeof(mybuffer)); /*读取输入。*/

      if(send(s,mybuffer,sizeof(mybuffer),0)<0)  /*发送信息。*/
{
perror("send");        /*错误处理。*/
exit(1);
}
else
{
bzero(mybuffer,sizeof(mybuffer));   /*清空mybuffer内存。*/
recv(s ,mybuffer,sizeof(mybuffer),0);  /*接收信息。*/
printf("received:%s\n",mybuffer);   /*输出信息。*/
}
}
}

 gcc 17.26.c -o tcpcli

chmod +x udpcli