How do C++ functions handle network protocols in network programming?

The C standard library provides the following functions to handle network protocols: socket(): Create a new network socket descriptor. connect(): Connect the socket to the remote address and port. send()/recv(): Send or receive data packets. listen(): Listens for incoming connections on the specified port. accept(): Accepts an incoming connection and creates a new socket descriptor.

C functions handle network protocols in network programming

A network protocol is a set of rules and conventions that control how computers communicate on a network. The C language provides rich functionality for developing network applications, including built-in functions for working with network protocols.

C functions for network protocols

The C standard library provides the following functions to handle network protocols:

• socket(): Create new The network socket descriptor.
• connect(): Connect the socket to the remote address and port.
• send()/recv(): Send or receive data packets.
• listen(): Listens for incoming connections on the specified port.
• accept(): Accepts an incoming connection and creates a new socket descriptor.

Practical Example: TCP Client-Server

The following example demonstrates how to use these functions to implement a simple TCP client-server protocol in a C application:

// 客户端代码
#include <iostream>
#include <netdb.h>
#include <sys/socket.h>

int main() {
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));

    // 获取服务器的地址和端口号
    char *host = "127.0.0.1";
    int port = 8080;

    // 创建套接字
    int sock = socket(AF_INET, SOCK_STREAM, 0);

    // 设置服务器地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(host);
    server_addr.sin_port = htons(port);

    // 连接到服务器
    connect(sock, (struct sockaddr *) &server_addr, sizeof(server_addr));

    // 发送数据到服务器
    std::string message = "Hello from client!";
    send(sock, message.c_str(), message.length(), 0);

    // 接收服务器的响应
    char buffer[1024];
    memset(buffer, 0, sizeof(buffer));
    recv(sock, buffer, sizeof(buffer), 0);

    // 输出服务器响应
    std::cout << "Received from server: " << buffer << std::endl;

    return 0;
}

// 服务器代码
#include <iostream>
#include <netdb.h>
#include <sys/socket.h>
#include <unistd.h>

int main() {
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));

    // 设置服务器的地址和端口号
    char *host = "127.0.0.1";
    int port = 8080;

    // 创建套接字
    int sock = socket(AF_INET, SOCK_STREAM, 0);

    // 设置服务器地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(host);
    server_addr.sin_port = htons(port);

    // 绑定套接字到服务器地址
    bind(sock, (struct sockaddr *) &server_addr, sizeof(server_addr));

    // 开始侦听传入连接
    listen(sock, 5);

    while (true) {
        struct sockaddr_in client_addr;
        memset(&client_addr, 0, sizeof(client_addr));
        socklen_t client_addr_len = sizeof(client_addr);

        // 接受传入连接
        int client_sock = accept(sock, (struct sockaddr *) &client_addr, &client_addr_len);

        // 从客户端接收数据
        char buffer[1024];
        memset(buffer, 0, sizeof(buffer));
        recv(client_sock, buffer, sizeof(buffer), 0);

        // 发送响应到客户端
        std::string message = "Hello from server!";
        send(client_sock, message.c_str(), message.length(), 0);

        // 关闭客户端套接字
        close(client_sock);
    }

    return 0;
}

By calling C network programming functions, you can easily implement multiple network protocols. These functions provide a clean and efficient interface to handle the low-level details of network communication, allowing you to focus on your application logic.

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