C++ Socket Programming: TCP Communication Guide

In C++, TCP communication is typically implemented using Socket programming. Below is a simple example code for establishing a TCP connection and sending/receiving data:

#include <iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>

int main() {
    // 创建socket
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
    
    if (client_socket < 0) {
        std::cerr << "Error creating socket" << std::endl;
        return 1;
    }
    
    // 设置服务器地址和端口
    struct sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(12345);
    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
    
    // 连接到服务器
    if (connect(client_socket, (struct sockaddr *)&server_address, sizeof(server_address)) < 0) {
        std::cerr << "Error connecting to server" << std::endl;
        return 1;
    }
    
    // 发送数据
    const char *message = "Hello from client!";
    if (send(client_socket, message, strlen(message), 0) < 0) {
        std::cerr << "Error sending message" << std::endl;
        return 1;
    }
    
    // 接收数据
    char buffer[1024] = {0};
    if (recv(client_socket, buffer, 1024, 0) < 0) {
        std::cerr << "Error receiving message" << std::endl;
        return 1;
    }
    
    std::cout << "Server response: " << buffer << std::endl;
    
    // 关闭socket
    close(client_socket);
    
    return 0;
}

In this example, we start by creating a client socket, then setting the server address and port. We then connect to the server using the connect function, send a message, receive a response from the server, and finally close the socket.

Please note that this is just a simple example and real-world scenarios may be more complex. In actual applications, you may need to handle errors, timeouts, and packet bundling issues. You can also use third-party libraries such as Boost.Asio to simplify the implementation of TCP communication.