代码示例_网络编程_select

select_多路复用

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1.头文件

#pragma once

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <strings.h>
#include <string.h>
#include <arpa/inet.h>

#define IP "192.168.2.150"
#define PORT 9999
#define SIZE 128

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2.client_select

#include "net.h"

int main(void)
{
    //1.创建套接字
    int fd = socket(AF_INET,SOCK_STREAM,0);
    if(fd<0){
        perror("socket failed");
        exit(1);
    }


    //2.初始服务器地址
    struct sockaddr_in cli;
    cli.sin_family = AF_INET;
    cli.sin_port = htons(PORT);
    cli.sin_addr.s_addr=inet_addr(IP);


    //3.发起连接请求
    if(  connect(fd,(struct sockaddr*)&cli,sizeof(cli))<0  ){
        perror("connect failed");
        exit(1);
    }


    //4.写
    char buf[SIZE];
    while(1){
    bzero(buf,SIZE);
    printf("please input:\t");
    fgets(buf,SIZE,stdin);
    write(fd,buf,strlen(buf));
        if(!strncmp(buf,"quit",4))
        break;
    }


    //5.关闭
    close(fd);


    return 0 ;
}

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3.server_select

#include "net.h"

int main(void)
{
    char buf[SIZE];
    int  newfd = -1;

    //1.创建套接字
    int fd = socket(AF_INET,SOCK_STREAM,0);
    if(fd<0){
        perror("socket failed");
        exit(1);
    }


    //2.初始本地地址
    struct sockaddr_in ser;
    ser.sin_family = AF_INET;
    ser.sin_port = htons(PORT);
    ser.sin_addr.s_addr=htonl(INADDR_ANY);


    //3.绑定
    if(  bind(fd,(struct sockaddr*)&ser,sizeof(ser))<0  ){
        perror("bind failed");
        exit(1);
    }

    //4.监听
    if(  listen(fd,5)<0  ){
        perror("listen failed");
        exit(1);
    }

    int len = sizeof(ser);
    
    
    //5.多路复用
    fd_set read_fds;    //定义读集合
    FD_ZERO(&read_fds); //清空读集合
    int maxfd = fd;        //最大描述符


    //6.加入监听处理 读集合
    while(1){
    FD_SET(0,&read_fds);  //将标准输入加入读集合
    FD_SET(fd,&read_fds); //将fd加入读集合
    maxfd = fd;           //表示最大读集合
    if(maxfd < newfd){
        FD_SET(newfd,&read_fds);
        maxfd = newfd;
    }

    int ret = select(maxfd+1,&read_fds,NULL,NULL,NULL);
    if(ret<0){
        perror("select failed");
        exit(1);
    }
    else if(ret==0){
        perror("time out");
        break;
    }
    else{
        //6.1 判断输入端是否有相应
        if(FD_ISSET(0,&read_fds)){
            bzero(buf,SIZE);
            fgets(buf,SIZE,stdin);
            printf("shell :%s",buf);
        }
        //6.2判断客户端是否有相应
        if(FD_ISSET(fd,&read_fds)){
            //接收
            newfd=accept(fd,(struct sockaddr*)&ser,&len);
            if(newfd<0){
                perror("accept failed");
                exit(1);
            }
            printf("client connect succsee :  ip=%s   port=%d  用户上线啦 ^.^ ...\n",inet_ntoa(ser.sin_addr),ntohs(ser.sin_port));
        }
        //6.3判断客户端是否有数据
        if(FD_ISSET(newfd,&read_fds)){
            bzero(buf,SIZE);    // 读之前清理一下，要不然内存可能有残余保留！！
            int val=read(newfd,buf,SIZE);
            if(val<0){
                perror("read failed");
                exit(1);
            }
            else if(val==0){
                FD_CLR(newfd,&read_fds);
                close(newfd);
                newfd=-1;
            }
            else{
                printf("client info :\nip=%s  port=%d\ndata=%s\n",inet_ntoa(ser.sin_addr),ntohs(ser.sin_port),buf);
                if(!strncmp(buf,"quit",4))
                    printf("client info :\nip=%s  port=%d  用户下线啦 ^.^ ...\n",inet_ntoa(ser.sin_addr),ntohs(ser.sin_port));
            }
        }    
    }
    }

    
    return 0 ;
}

测试：

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success  ！