Linux系统编程之多线程并发服务器简单实现

服务端
当有客户端连接服务端后，客户端发送小写字母，服务端转换为大写字母后发送给客户端

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<fcntl.h>
#include<string.h>
#include<pthread.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#define IP "127.0.0.1"
#define PORT 7777
int cfd;
void* do_work(void* arg){
    int i = (int)arg;
    printf("第%d个子线程连接\n",i);
    char buf[BUFSIZ];
    int len;
    int j;
    while(1){
        len = read(cfd,buf,sizeof(buf));
        if(len == 0){
            printf("客户端已经关闭\n");
            break;
        }
        for(j = 0; j < len; j++){
            buf[j] = toupper(buf[j]);
        }
        write(cfd,buf,len);
    }
    return ;
}

int main(){
    //1、建立套接字
    int sfd = socket(AF_INET,SOCK_STREAM,0);
    //2、绑定
    struct sockaddr_in serv_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    inet_pton(AF_INET,IP,&serv_addr.sin_addr.s_addr);
    socklen_t serv_len = sizeof(serv_addr);
    int ret = bind(sfd,(struct sockaddr*)&serv_addr,serv_len);
    if(ret == -1){
        perror("bind eror");
        exit(1);
    }
    //3、监听 设置最大连接数
    ret = listen(sfd,128);
    if(ret != 0){
        perror("listen error");
        printf("listen error:%s\n",strerror(ret));
        exit(2);
    }
    //4、开始使用多线程 主线程接受连接，子进程处理每个连接
    struct sockaddr_in clie_addr;
    socklen_t clie_len = sizeof(clie_addr);
    int i = 0;
    pthread_t tid[128];
    char buf[BUFSIZ];
    while(1){
        cfd = accept(sfd,(struct sockaddr *)&clie_addr,&clie_len);
        printf("%s连接，端口为：%d\n",inet_ntop(AF_INET,&clie_addr.sin_addr.s_addr,buf,sizeof(buf)),ntohs(clie_addr.sin_port));
        //创建子线程
        ret = pthread_create(&tid[i],NULL,do_work,(void*)i);
        if(ret != 0){
            printf("pthread_create error:%s\n",strerror(ret));
            exit(3);
        }
        //采用线程分离的方式，自动回收子线程资源
        pthread_detach(tid[i]);
        i++;
    }

    return 0;
｝