Linux下实现客户端和服务器端的通信

首先，可以将代码复制下来放到U盘里，然后挂载到Linux上

挂载步骤

找到设备->USB->你U盘的名字

挂载成功

访问U盘把代码拷贝到home文件夹下，就可以直接进行编译。

client.c

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

    #define PORT 1234
    #define MAXDATASIZE 100  

    char receiveM[];
        char sendM[]; 

    int main(int argc, char *argv[])
 {
    int fd, numbytes;
    struct hostent *he;
    struct sockaddr_in server;  

    //检查用户输入，如果用户输入不正确，提示用户正确的输入方法
    if (argc !=) {         printf("Usage: %s <IP Address>\n",argv[]);
    exit();
    } 

    // 通过函数 gethostbyname()获得字符串形式的ip地址，并赋给he
    if ((he=gethostbyname(argv[]))==NULL){
    printf("gethostbyname() error\n");
    exit();
    } 

    // 产生套接字fd
    if ((fd=socket(AF_INET, SOCK_STREAM, ))==-){
    printf("socket() error\n");
    exit();
    } 

    bzero(&server,sizeof(server));

    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr = *((struct in_addr *)he->h_addr);
    if(connect(fd, (struct sockaddr *)&server,sizeof(struct sockaddr))==-){
    printf("connect() error\n");
    exit();
    } 

    // 向服务器发送数据

    printf("send message to server:");

        fgets(sendM,,stdin);
    int send_le;
        send_le=strlen(sendM);
    sendM[send_le-]='\0';

        send(fd,sendM,strlen(sendM),); 

    // 从服务器接收数据
    if ((numbytes=recv(fd,receiveM,MAXDATASIZE,)) == -){
    printf("recv() error\n");
    exit();
    } 

        printf("receive message from server:%s\n",receiveM);

    close(fd); 

 }

server.c

    #include <stdio.h>
    #include <string.h>
    #include <strings.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include<pthread.h>
    #define PORT 1234
    #define BACKLOG 1 

void *start_routine( void *ptr)
{
    int fd = *(int *)ptr;
    char buf[];
        int numbytes;
    int i,c=;
    printf("this is a new thread,you got connected\n");
    printf("fd=%d\n",fd);

    if ((numbytes=recv(fd,buf,,)) == -){
    printf("recv() error\n");
    exit();
    } 

    char str[numbytes];
    char buffer[numbytes];

    //将收到的字符串反转
    for(c=;c<(numbytes-);c++)
    {
    buffer[c]=buf[c];
    }

        printf("receive message:%s\n",buf);

    printf("numbytes=%d\n",numbytes);

    for(i=;i<numbytes;i++)
    {
        str[i]=buf[numbytes--i];

    }

    printf("server will send:%s\n",str);
    numbytes=send(fd,str,sizeof(str),);
    printf("send numbytes=%d\n",numbytes);
    close(fd);
}

int  main()
{ 

    int listenfd, connectfd;
    struct sockaddr_in server;
    struct sockaddr_in client;
    int sin_size;
    sin_size=sizeof(struct sockaddr_in); 

    pthread_t thread; //定义一个线程号

    if ((listenfd = socket(AF_INET, SOCK_STREAM, )) == -)
    {
        perror("Creating socket failed.");
        exit();
    }

    int opt = SO_REUSEADDR;
    setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    bzero(&server,sizeof(server));  

    server.sin_family=AF_INET;
    server.sin_port=htons(PORT);
    server.sin_addr.s_addr = htonl (INADDR_ANY); 

    // 绑定
    if (bind(listenfd, (struct sockaddr *)&server, sizeof(struct sockaddr)) == -) {
    perror("Bind error.");
    exit();
    }   

    // 监听
    if(listen(listenfd,BACKLOG) == -){  /* calls listen() */
    perror("listen() error\n");
    exit();
    } 

    while()
    {
        // accept
        if ((connectfd = accept(listenfd,(struct sockaddr *)&client,&sin_size))==-) {
        perror("accept() error\n");
        exit();
        }

        printf("You got a connection from %s\n",inet_ntoa(client.sin_addr) ); 

        pthread_create(&thread,NULL,start_routine,(void *)&connectfd);

    }
    close(listenfd);

}

代码从U盘复制到home后，编译执行

打开三个中端

可以发现用户端和服务器端连接成功，即用户端发送的信息，服务器端可以接收的到。