一  效果展示

持续互相通信，上面是服务端，下面为客户端加上ip，最后客户端输入exit退出

 二 代码展示

服务端

/*server.c*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netinet/in.h>
#include <netdb.h>
#define portnumber           3333
int main(int argc ,char *argv[])
{
	struct sockaddr_in server_addr;
	struct sockaddr_in client_addr;
	int sin_size;
	int nbytes;
	int sockfd, new_fd;
	char buffer[1024];
	char sendbuf[1024];

	/*建立socket连接*/
	if ((sockfd = socket(AF_INET,SOCK_STREAM,0))== -1)
	{
		fprintf(stderr,"Socket error :%s\n\a",strerror(errno));
		exit(1);
	}
	printf("socket id=%d",sockfd);

	/*设置sockaddr_in 结构体中相关参数*/
	bzero(&server_addr,sizeof(struct sockaddr_in));
	server_addr.sin_family = AF_INET;

	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	//server_addr.sin_addr.s_addr = inet_addr("192.168.1.1");
	server_addr.sin_port = htons(portnumber);
	/*绑定函数bind()*/
	if (bind(sockfd, (struct sockaddr *) (&server_addr), 
				sizeof(struct sockaddr)) == -1)
	{
		fprintf(stderr,"Bind error :%s\n\a",strerror(errno));
		exit(1);
	}
	printf("binding succeed!\n");
	/*调用listen()函数，创建未处理请求的队列*/
	if (listen(sockfd,5) == -1)
	{
		fprintf(stderr,"Listen error :%s\n\a",strerror(errno));
		exit(1);
	}
	printf("Listening...\n");
	/*调用accept()函数，等待客户端的连接*/
	while(1)
	{
		memset(buffer,0x00,1024);
		sin_size =sizeof(struct sockaddr_in);
		if ((new_fd = accept(sockfd, 
						(struct sockaddr *)&client_addr, &sin_size)) == -1)
		{
			fprintf(stderr,"Accept error :%s\n\a",strerror(errno));
			exit(1);
		}
		fprintf(stderr,"Server get connection from %d\n",inet_ntoa   (client_addr.sin_addr));
		if ((nbytes = read(new_fd, buffer,1024)) == -1)
		{
			fprintf(stderr,"Read error :%s\n\a",strerror(errno));
			exit(1);
		}
		char content[1024];
		if (strlen(buffer)>0)
		{
			buffer[nbytes] = '\0';
			printf("Server received  %s\n", buffer);
				if(strncmp(buffer, "exit", 4)==0)
			{
				close(sockfd);
				exit(0);
			}
			else
			{
					/*发送消息给服务器端*/
					printf("Input to client: ");
					fgets(content,1024,stdin);
					send(new_fd,content,strlen(content),0);
			}
			
		}
		close(new_fd);
	}
	exit(0);
}

 客户端

/*client.c*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define portnumber           3333
int main(int argc, char *argv[])
{
	int sockfd;
	int recvbytes;
	char buffer[1024];
	char revbuf[1024];
	struct hostent *host ;
	struct sockaddr_in server_addr;

	if(argc != 2)
	{
		fprintf(stderr,"Usage :%s hostname \a\n",argv[0]);
		exit(1);
	}

	/*地址解析函数*/
	if ((host = gethostbyname(argv[1])) == NULL)
	{
		fprintf(stderr,"Gethostbyname error\n");
		exit(1);
	}


	
	while(1){

			/*创建socket*/
		if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
		{
			fprintf(stderr,"Socket Error :%s\a\n",strerror(errno));
			exit(1);
		}
		/*设置sockaddr_in 结构体中相关参数*/
		bzero(&server_addr,sizeof(server_addr));
		server_addr.sin_family = AF_INET;
		server_addr.sin_port = htons(portnumber);
		server_addr.sin_addr = *((struct in_addr *)host->h_addr);
		/*调用connect函数主动发起对服务器端的连接*/
			if(connect(sockfd,(struct sockaddr *) (&server_addr), 
						sizeof(struct sockaddr))== -1)
			{
				fprintf(stderr,"Connect Error :%s\a\n",strerror(errno));
				exit(1);
			}
			
		printf("Input to server: ");

		/*发送消息给服务器端*/
		fgets(buffer,1024,stdin);
		//write(sockfd, buffer, strlen(buffer));
		send(sockfd,buffer,strlen(buffer),0);
		/*调用recv()函数接收客户端的请求*/
		memset(revbuf, 0, sizeof(revbuf));
		if ((recvbytes = recv(sockfd, revbuf, sizeof(revbuf), 0)) == -1)
		{
			perror("recv");
			exit(1);
		}
		printf("Received a message: %s\n", revbuf);
		close(recvbytes);
		close(sockfd);
	}
	
	exit(0);
}