close(socket_fd)

`close(socket_fd)` 是用于关闭套接字文件描述符（socket_fd）的操作。在Python中，如果你使用socket库创建了一个网络连接或服务器监听，`socket_fd` 是代表该连接的文件描述符。调用 `close()` 函数后，套接字将不再接收或发送数据，并且连接会被终止。

下面是一个简单的例子：

import socket

# 创建一个socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# 假设已经连接到服务器
server_address = ('localhost', 10000)
sock.connect(server_address)

# 连接后，可以使用close()关闭套接字
sock.close()

在这个示例中，`sock.close()` 关闭了与服务器的连接。注意，如果你不手动关闭套接字，操作系统通常会在进程结束时自动关闭它，但在资源管理上还是推荐尽早关闭。

相关问题

修改client.c： #include<stdio.h> #include<stdlib.h> #include<string.h> #include<errno.h> #include<sys/types.h> #include<sys/socket.h> #include<netinet/in.h> int main() { int ret = 0; int socket_fd; char buffer[100]="你好，我是xxx!"; struct sockaddr_in server_add; socket_fd = socket(AF_INET, SOCK_STREAM, 0); if(-1 == socket_fd) { printf("socket fail ! \r\n"); return -1; } bzero(&server_add,sizeof(struct sockaddr_in)); server_add.sin_family=AF_INET; server_add.sin_addr.s_addr= inet_addr("192.168.1.2"); server_add.sin_port=htons(8888); if(-1 == connect(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) { printf("connect fail !\r\n"); return -1; } ret = write(socket_fd, buffer, strlen(buffer)); if(-1 == ret ) { printf("write fail!\r\n"); return -1; } close(socket_fd); return 0; }server.c： #include<stdio.h> #include<stdlib.h> #include<string.h> #include<errno.h> #include<sys/types.h> #include<sys/socket.h> #include<netinet/in.h> int main() { int ret = 0; int socket_fd, new_socket_fd; struct sockaddr_in server_add,client_add; int add_len; char recv_buff[100]={0}; char send_buff[100]="朕xxx知道了!"; socket_fd = socket(AF_INET, SOCK_STREAM, 0); if(-1 == socket_fd) { printf("socket fail ! \r\n"); return -1; } bzero(&server_add,sizeof(struct sockaddr_in)); server_add.sin_family=AF_INET; server_add.sin_addr.s_addr=htonl(INADDR_ANY); server_add.sin_port=htons(8888); if(-1 == bind(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) { printf("bind fail !\r\n"); return -1; } if(-1 == listen(socket_fd,5)) { printf("listen fail !\r\n"); return -1; } while(1) { new_socket_fd = accept(socket_fd, (struct sockaddr *)(&client_add), &add_len); if(-1 == new_socket_fd) { printf("accept fail !\r\n"); return -1; } ret = read(new_socket_fd, recv_buff,100); if(-1 == ret) { printf("read data fail !\r\n"); return -1; } printf("Now we get:%s from client!\n", recv_buff); ret = write(socket_fd, send_buff, strlen(send_buff)); if(-1 == ret ) { printf("write fail!\r\n"); return -1; } close(new_socket_fd); } close(socket_fd); return 0; }修改服务器和客户端，使朕知道了正常输出

修改后的client.c：

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

int main() {
    int ret = 0;
    int socket_fd;
    char buffer[100]="你好，我是xxx!";
    struct sockaddr_in server_add;

    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if(-1 == socket_fd)
    {
        printf("socket fail ! \r\n");
        return -1;
    }

    bzero(&server_add,sizeof(struct sockaddr_in));
    server_add.sin_family=AF_INET;
    server_add.sin_addr.s_addr= inet_addr("192.168.1.2");
    server_add.sin_port=htons(8888);

    if(-1 == connect(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr)))
    {
        printf("connect fail !\r\n");
        return -1;
    }

    ret = write(socket_fd, buffer, strlen(buffer));
    if(-1 == ret )
    {   
        printf("write fail!\r\n");
        return -1;
    }

    ret = read(socket_fd, buffer,100);
    if(-1 == ret) {
        printf("read data fail !\r\n");
        return -1;
    }

    printf("Now we get:%s from server!\n", buffer);

    close(socket_fd);
    return 0;
}

修改后的server.c：

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

int main() {
    int ret = 0;
    int socket_fd, new_socket_fd;
    struct sockaddr_in server_add,client_add;
    int add_len;
    char recv_buff[100]={0};
    char send_buff[100]="朕xxx知道了!";

    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if(-1 == socket_fd) {
        printf("socket fail ! \r\n");
        return -1;
    }

    bzero(&server_add,sizeof(struct sockaddr_in));
    server_add.sin_family=AF_INET;
    server_add.sin_addr.s_addr=htonl(INADDR_ANY);
    server_add.sin_port=htons(8888);

    if(-1 == bind(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) {
        printf("bind fail !\r\n");
        return -1;
    }

    if(-1 == listen(socket_fd,5)) {
        printf("listen fail !\r\n");
        return -1;
    }

    while(1) {
        new_socket_fd = accept(socket_fd, (struct sockaddr *)(&client_add), &add_len);
        if(-1 == new_socket_fd) {
            printf("accept fail !\r\n");
            return -1;
        }

        ret = read(new_socket_fd, recv_buff,100);
        if(-1 == ret) {
            printf("read data fail !\r\n");
            return -1;
        }

        printf("Now we get:%s from client!\n", recv_buff);

        ret = write(new_socket_fd, send_buff, strlen(send_buff));
        if(-1 == ret ) {
            printf("write fail!\r\n");
            return -1;
        }

        close(new_socket_fd);
    }

    close(socket_fd);
    return 0;
}

在客户端发送消息后，服务器会返回“朕xxx知道了!”，客户端会输出“Now we get:朕xxx知道了! from server!”。

翻译这段代码并在每一行后进行注释int ret,listen_fd, client_fd; struct sockaddr_in server_addr, client_addr; socklen_t slen, clen = sizeof(client_addr); char recvBuffer[128] = {0}; char recCmd[128] = {0}; const int on = 1; listen_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if(listen_fd < 0) { printf("server socket failed\n"); exit(1); } server_addr.sin_family = AF_INET; server_addr.sin_port = htons(SERVERPT); server_addr.sin_addr.s_addr = htons(INADDR_ANY); slen = sizeof(server_addr); //绑定网络设备 setsockopt(listen_fd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on)); ret = bind(listen_fd, (struct sockaddr *)&server_addr, slen); if(ret < 0) { printf("listen_fd bind failed\n"); exit(1); } ret = listen(listen_fd, 8); if(ret < 0) { printf("server listen failed\n"); exit(2); } //开始侦听客户端的连接请求 printf("Waiting connect.....\n"); client_fd = accept(listen_fd, (struct sockaddr *)&client_addr, (socklen_t *)&clen); if(client_fd < 0) { printf("server accept failed\n"); exit(3); } //连接成功，打印客户端的网卡信息 printf("client port: %d ,", ntohs(client_addr.sin_port)); printf("client ip: %s\n",inet_ntoa(client_addr.sin_addr)); while(1) { printf("Waiting recv.....\n"); ret = read(client_fd, recvBuffer, 128); if(ret < 0) printf("read failed\n"); else if(ret == 0) { //客户端下线 close(client_fd); break; } else { //打印接收到客户端信息 printf("client data: %s\n", recvBuffer); //给客户端回发信息 write(client_fd, "Successfully received your message!", 128); } }

/* 定义三个变量：ret, listen_fd, client_fd */
int ret, listen_fd, client_fd;
/* 定义两个结构体变量：server_addr, client_addr */
struct sockaddr_in server_addr, client_addr;
/* 定义两个变量：slen, clen，slen记录server_addr的大小，clen记录client_addr的大小 */
socklen_t slen, clen = sizeof(client_addr);
/* 定义两个字符数组：recvBuffer、recCmd，长度都为128，初始化为0 */
char recvBuffer[128] = {0};
char recCmd[128] = {0};
/* 定义一个常量on为1，表示开启相关选项 */
const int on = 1;
/* 创建一个TCP协议的套接字，返回一个文件描述符 */
listen_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
/* 如果listen_fd小于0，表示创建套接字失败，输出提示信息并结束程序 */
if(listen_fd < 0) {
printf("server socket failed\n");
exit(1);
}
/* 设置server_addr结构体的属性 */
server_addr.sin_family = AF_INET; //地址族为IPv4
server_addr.sin_port = htons(SERVERPT); //端口号，需要用htons转换为网络字节序
server_addr.sin_addr.s_addr = htons(INADDR_ANY); //IP地址，使用INADDR_ANY表示本机任意IP地址
slen = sizeof(server_addr); //记录server_addr结构体的大小
/* 设置socket选项，允许地址重用 */
setsockopt(listen_fd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));
/* 绑定网络设备和端口，将socket与server_addr绑定 */
ret = bind(listen_fd, (struct sockaddr *)&server_addr, slen);
/* 如果绑定失败，输出提示信息并结束程序 */
if(ret < 0) {
printf("listen_fd bind failed\n");
exit(1);
}
/* 开始侦听客户端的连接请求，最多连接8个客户端 */
ret = listen(listen_fd, 8);
/* 如果侦听失败，输出提示信息并结束程序 */
if(ret < 0) {
printf("server listen failed\n");
exit(2);
}
/* 输出等待客户端连接的提示信息 */
printf("Waiting connect.....\n");
/* 接受客户端连接请求，返回一个文件描述符 */
client_fd = accept(listen_fd, (struct sockaddr *)&client_addr, (socklen_t *)&clen);
/* 如果接受请求失败，输出提示信息并结束程序 */
if(client_fd < 0) {
printf("server accept failed\n");
exit(3);
}
/* 连接成功，打印客户端的网卡信息 */
printf("client port: %d ,", ntohs(client_addr.sin_port));
printf("client ip: %s\n",inet_ntoa(client_addr.sin_addr));
/* 进入循环，不断接收客户端发送的消息并回复 */
while(1) {
/* 输出等待接收数据的提示信息 */
printf("Waiting recv.....\n");
/* 读取客户端发送的数据，返回读取到的字节数 */
ret = read(client_fd, recvBuffer, 128);
/* 如果读取失败，输出提示信息 */
if(ret < 0)
printf("read failed\n");
/* 如果读取到的字节数为0，表示客户端已下线，关闭连接并跳出循环 */
else if(ret == 0) {
close(client_fd);
break;
}
/* 如果读取到了数据，打印接收到的消息，并回复客户端 */
else {
printf("client data: %s\n", recvBuffer);
write(client_fd, "Successfully received your message!", 128);
}
}