IO多路复用，解决阻塞问题

server:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<sys/select.h>
#include<sys/time.h>

#define PORT 2222 
typedef struct sockaddr SA;
typedef struct sockaddr_in SSA;

int main()
{
	//创建监听的套接口
	int sockfd=socket(AF_INET,SOCK_STREAM,0);
	if(sockfd < 0)
	{
		perror("socket error!
");
		exit(1);
	}

	//bind
	//
	struct sockaddr_in my_addr;	
	struct sockaddr_in client_addr;	

	my_addr.sin_family=AF_INET;	
	my_addr.sin_port=htons(PORT);	
	my_addr.sin_addr.s_addr=inet_addr("192.168.71.104");	

	int ret=0;
	if(bind(sockfd,(SA*)&my_addr,sizeof(SA))< 0)	
	{
		perror("bind error!
");
		exit(1);
	}
	//listen
	//
	//
	if(listen(sockfd,10)< 0)
	{
		perror("listen error!
");
		exit(1);
	}
	printf("listen.......
");

	//创建新套接发送
	int ssalen=sizeof(struct sockaddr_in);
	int nfd=accept(sockfd,(SA*)&client_addr,&ssalen);
	if(nfd<0)
	{
		perror("accept error!
");
		exit(1);
	}
	printf("accpet from %s
",inet_ntoa(client_addr.sin_addr));

	while(1)
	{
		//IO多路复用	
		fd_set st;
		FD_ZERO(&st);
		FD_SET(0,&st);
		 FD_SET(nfd,&st);
		ret=select(nfd+1,&st,0,0,0);	
			//剥夺nfd的控制权
		if(FD_ISSET(nfd,&st))
		{
				//接收数据
		   	 char buf[50]={0};
		   	 if(recv(nfd,buf,50,0)<0)
		   	 {
		   	 	perror("recv error!
");
		   	 	exit(1);
		   	 }
		   	 printf("client said : %s
",buf);

		}	
		
		if(FD_ISSET(0,&st))
		{
	   	 //发送数据
	   		 char send_buf[50]={0};
	   		 memset(send_buf,0,50);
	   		 ret=read(0,send_buf,50);
	   		 if(ret<0)
	   		 {
	   		     perror("read error!
");
	   		     exit(1);
	   		 }
	
	   		 printf("get %s
",send_buf);
	   		 if(send(nfd,send_buf,strlen(send_buf),0)<0)    
	   		 {
	   		     perror("send error!
");
	   		     exit(1);
	   		 }
	   		 printf("send is %s
",send_buf);
		}
	}
	
}

　　

client:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>

#define PORT 2222 
typedef struct sockaddr SA;
typedef struct sockaddr_in SSA;

int main()
{
	//创建监听的套接口
	int sockfd=socket(AF_INET,SOCK_STREAM,0);
	if(sockfd < 0)
	{
		perror("socket error!
");
		exit(1);
	}

	//建立连接
	//connect
	struct sockaddr_in server_addr;	
	server_addr.sin_family=AF_INET;	
	server_addr.sin_port=htons(PORT);	
	server_addr.sin_addr.s_addr=inet_addr("192.168.71.104");	
	
	if(connect(sockfd,(SA*)&server_addr,sizeof(server_addr)) < 0)	
	{
		perror("connect error!
");
		exit(1);
	}	

	printf("conncet sucess!
");

	while(1)
	{
	     fd_set st;
         FD_ZERO(&st);
         FD_SET(0,&st);
         FD_SET(sockfd,&st);
			select(sockfd+1,&st,0,0,0);

        if(FD_ISSET(0,&st))
        {

		//send
			char buf[50]={0};
			int ret=read(0,buf,50);
			if(ret<0)
			{
				perror("read error!
");
				exit(1);
			}
		
			if(send(sockfd,buf,strlen(buf),0)<0)	
			{
				perror("send error!
");
				exit(1);
			}
			printf("send is %s
",buf);
		}

		//recv	
        if(FD_ISSET(sockfd,&st))
        {
			char recv_buf[50]={0};
		    if(recv(sockfd,recv_buf,50,0)<0)
		    {
		        perror("recv error!
");
		        exit(1);
		    }
		    printf("server said : %s
",recv_buf);
		}
	}	

}