16.17.c

基于Linux的网络编程！

#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>

#define REMOTEPORT 4567
#define REMOTEIP "127.0.0.1"

int   main(int argc,char *argv[])
{
    int s,len;
    struct sockaddr_in addr;
    int addr_len;
    char msg[256];
    int i=0;  
   
    if (( s= socket(AF_INET, SOCK_DGRAM, 0) )<0)
    {
        perror("error");
        exit(1);
    }
    else
    {
    	printf("socket created .\n");
    	printf("socked id: %d \n",s);
    	printf("remote ip: %s \n",REMOTEIP);
    	printf("remote port: %d \n",REMOTEPORT);
    }
      
    len=sizeof(struct sockaddr_in);
    bzero(&addr,sizeof(addr));
    addr.sin_family=AF_INET;
    addr.sin_port=htons(REMOTEPORT);
    addr.sin_addr.s_addr=inet_addr(REMOTEIP);
            
    while (1)
    {
    	bzero(msg,sizeof(msg));
        len = read(STDIN_FILENO,msg,sizeof(msg));
        sendto(s,msg,len,0,&addr,addr_len);
        printf("\nInput message: %s \n",msg);
        len= recvfrom (s,msg,sizeof(msg),0,&addr,&addr_len);/*这是接收到的信息。*/
        printf("%d :",i);
        i++;
        printf("Received message: %s \n",msg);/*这是服务器返回的信息。*/
    }   
}