基于UDP套接字编程实例

data.h

 #ifndef DATA_H
 #define DATA_H
 #include <stdio.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <errno.h>
 #define PORT 4578
 #define maxn 100

 #endif

server.c

 #include "data.h"
 int main()
 {
     int sockfd;
     struct sockaddr_in server;
     struct sockaddr_in client;
     socklen_t len;
     int num;
     char buf[maxn];
     if((sockfd = socket(AF_INET,SOCK_DGRAM,)) == -)
     {
         fprintf(stderr,"socket fail,error:%s\n",strerror(errno));
         return -;
     }
     bzero(&server,sizeof(server));
     server.sin_family = AF_INET;
     server.sin_port = htons(PORT);
     server.sin_addr.s_addr = htonl(INADDR_ANY);
     if(bind(sockfd,(struct sockaddr*)&server,sizeof(server)) == -)
     {
         fprintf(stderr,"bind fail,error:%s\n",strerror(errno));
         return -;
     }
     len = sizeof(client);
     bzero(&buf,sizeof(buf));
     while()
     {
         num = recvfrom(sockfd,buf,maxn,,(struct sockaddr*)&client,&len);
         if(num < )
         {
             perror("recvfrom() error!\n");
             exit();
         }
         num--;
         buf[num] = '\0';
         printf("You got a message <%s> from client.\n",buf);
         printf("It is ip is %s,port is %d.\n",
             inet_ntoa(client.sin_addr), htons(client.sin_port));
         sendto(sockfd,buf,strlen(buf),,(struct sockaddr*)&client,len);
         if(!strcmp(buf,"bye"))
             break;
     }
     close(sockfd);

 }

client.c

#include "data.h"
int main()
{
    int sockfd,num;
    char sendbuf[maxn];
    char recvbuf[maxn];
    struct sockaddr_in server;
    struct sockaddr_in peer;
    if((sockfd = socket(AF_INET,SOCK_DGRAM,)) == -)
    {
        fprintf(stderr,"socket fail,error %s\n",strerror(errno));
        exit();
    }
    bzero(&server,sizeof(server));
    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr.s_addr = inet_addr("127.0.0.1");
    bzero(&sendbuf,sizeof(sendbuf));
    bzero(&recvbuf,sizeof(recvbuf));
    while(fgets(sendbuf,sizeof(sendbuf),stdin) != NULL)
    {
        int tt = strlen(sendbuf);
        sendto(sockfd,sendbuf,tt,,(struct sockaddr*)&server,sizeof(server));
        socklen_t len;
        recvfrom(sockfd,recvbuf,maxn,,NULL,NULL);
        printf("receive message is :");
        fputs(recvbuf,stdout);
        printf("\n");
        bzero(&sendbuf,sizeof(sendbuf));
        bzero(&recvbuf,sizeof(recvbuf));
    }
    close(sockfd);
    return ;
}

运行结果：