多进程版本

服务器

#include <arpa/inet.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <signal.h>
#include <string>
void mywait(int num)
{
    while(1)
    {
        pid_t pid=waitpid(-1,NULL,WNOHANG);//非阻塞回收进程
        if(pid>0)printf("回收了%d\n",pid);
        if(pid==0||pid==-1)break;
    }
}
int main()
{
    int flag=0;
    struct sockaddr_in saddr;
    saddr.sin_port = htons(8999);
    saddr.sin_addr.s_addr = INADDR_ANY;
    saddr.sin_family = AF_INET;
    int sfd = socket(AF_INET, SOCK_STREAM, 0);
    struct sigaction sig;
    sigemptyset(&sig.sa_mask);
    sig.sa_flags=0;
    sig.sa_handler=mywait;
    sigaction(SIGCHLD,&sig,NULL);//设置SIGCHLD信号捕捉
    if (sfd == -1)
    {
        perror("socket error");
        return 1;
    }
    flag = bind(sfd, (struct sockaddr*)&saddr, sizeof(struct sockaddr_in));
    if (flag == -1)
    {
        perror("bind error");
        return 1;
    }
    flag=listen(sfd, 100);
    if(flag==-1)
    {
        perror("listen error");
        return 1;
    }
    struct sockaddr_in caddr;
    int clen=sizeof(caddr);
    while (1)
    {
        int cfd = accept(sfd, (struct sockaddr*)&caddr, (socklen_t*)&clen);
        if (cfd == -1)
        {
            perror("accept error");
            continue;
        }
        char ip[1024]={'\0'};//必须加上，不然解析IP会失败
        printf("接收到了客户端%s:%d的连接\n",inet_ntop(AF_INET,&caddr.sin_addr,ip,1024),ntohs(caddr.sin_port));
        int pid=fork();
        if(pid==0)
        {
            close(sfd);
            while(1)
            {
                char buf[1024] = {'\0'};
                flag = recv(cfd, buf, 1024, 0);
                if (flag==-1)
                {
                    perror("read error");
                    break;
                }
                else if(flag==0)
                {
                    printf("连接断开\n");
                    break;
                }
                printf("从客户端收到数据:%s\n", buf);
                std::string sendstr="服务器收到了"+std::to_string(caddr.sin_port)+"的数据";
                flag = send(cfd, sendstr.c_str(), sendstr.length(), 0);
                if (flag == -1)
                {
                    perror("send error");
                    break;
                }
                memset(buf, 0, 1024);
            }
            exit(0);
        }
        else
        {
            close(cfd);
        }
    }
    return 0;
}

客户端

#include <arpa/inet.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <string>
int main()
{
    int flag;
    struct sockaddr_in* caddr=(struct sockaddr_in*)malloc(sizeof(struct sockaddr_in));
    inet_pton(AF_INET, "192.168.101.231", &caddr->sin_addr.s_addr);
    caddr->sin_family = AF_INET;
    caddr->sin_port = htons(8999);
    int cfd = socket(AF_INET, SOCK_STREAM, 0);
    if (cfd == -1)
    {
        perror("socket error");
        return 1;
    }
    flag= connect(cfd, (struct sockaddr*)caddr, sizeof(struct sockaddr));//caddr就是指针类型
    if (flag == -1)
    {
        perror("connect error");
        return 1;
    }
    int i=0;
    while (1)
    {
        char buf[1024] = {'\0'};
        std::string sendstr="我是客户端，我发送了"+std::to_string(i);
        flag = send(cfd,  sendstr.c_str(), sendstr.length(),0);
        if (flag == -1)
        {
            perror("send error");
            continue;
        }
        printf("send:%s\n", sendstr.c_str());
        flag = recv(cfd, buf, 1024, 0);
        if (flag == -1)
        {
            perror("recv error");
            continue;
        }
        printf("客户端收到数据:%s\n", buf);
        memset(buf, 0, 1024);
        i++;
        sleep(1);
    }
    close(cfd);
    return 0;
}

多线程版本服务器

#include <arpa/inet.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <string>
#include <pthread.h>
void* handle(void* arg)
{
    int flag=0;
    int* arr=(int*)arg;
    int cfd=arr[0];
    int port=arr[1];
    while(1)
    {
        char buf[1024] = {'\0'};
        flag = recv(cfd, buf, 1024, 0);
        if (flag==-1)
        {
            perror("read error");
            break;
        }
        else if(flag==0)
        {
            printf("连接断开\n");
            break;
        }
        printf("从客户端%d收到数据:%s\n",port,buf);
        std::string sendstr="服务器收到了"+std::to_string(port)+"的数据";
        flag = send(cfd, sendstr.c_str(), sendstr.length(), 0);
        if (flag == -1)
        {
            perror("send error");
            break;
        }
        memset(buf, 0, 1024);
    }
    close(cfd);
    return NULL;
}
int main()
{
    int flag=0;
    struct sockaddr_in saddr;
    saddr.sin_port = htons(8999);
    saddr.sin_addr.s_addr = INADDR_ANY;
    saddr.sin_family = AF_INET;
    int sfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sfd == -1)
    {
        perror("socket error");
        return 1;
    }
    flag = bind(sfd, (struct sockaddr*)&saddr, sizeof(struct sockaddr_in));
    if (flag == -1)
    {
        perror("bind error");
        return 1;
    }
    flag=listen(sfd, 100);
    if(flag==-1)
    {
        perror("listen error");
        return 1;
    }
    while (1)
    {
        struct sockaddr_in caddr;
        int clen=sizeof(caddr);
        int cfd = accept(sfd, (struct sockaddr*)&caddr, (socklen_t*)&clen);
        int port=ntohs(caddr.sin_port);
        printf("端口号:%d\n",port);
        if (cfd == -1)
        {
            perror("accept error");
            continue;
        }
        char ip[1024]={'\0'};//必须加上，不然解析IP会失败
        printf("接收到了客户端%s:%d的连接\n",inet_ntop(AF_INET,&caddr.sin_addr,ip,1024),port);
        pthread_t tid;
        int arg[2]={cfd,port};
        pthread_create(&tid,NULL,handle,(void*)arg);//这里不能传递cfd的地址，各个线程是共享这个地址的
        pthread_detach(tid);
    }
    return 0;
}

 运行效果：