如何用C++实现socket通讯

在C++中实现socket通讯需要使用操作系统提供的socket API。下面是一个简单的例子，展示了如何创建一个TCP服务器和一个TCP客户端进行通讯。

服务器端代码：

#include <iostream>
#include <winsock2.h>

using namespace std;

int main()
{
    // 初始化Winsock库
    WSADATA wsaData;
    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != 0) {
        cout << "WSAStartup failed: " << result << endl;
        return 1;
    }

    // 创建socket
    SOCKET listenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (listenSocket == INVALID_SOCKET) {
        cout << "socket failed: " << WSAGetLastError() << endl;
        WSACleanup();
        return 1;
    }

    // 绑定socket到本地IP和端口
    sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(12345);
    addr.sin_addr.s_addr = INADDR_ANY;
    result = bind(listenSocket, (sockaddr*)&addr, sizeof(addr));
    if (result == SOCKET_ERROR) {
        cout << "bind failed: " << WSAGetLastError() << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    // 监听socket
    result = listen(listenSocket, SOMAXCONN);
    if (result == SOCKET_ERROR) {
        cout << "listen failed: " << WSAGetLastError() << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    // 接受客户端连接
    sockaddr_in clientAddr;
    int clientAddrSize = sizeof(clientAddr);
    SOCKET clientSocket = accept(listenSocket, (sockaddr*)&clientAddr, &clientAddrSize);
    if (clientSocket == INVALID_SOCKET) {
        cout << "accept failed: " << WSAGetLastError() << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    // 从客户端接收数据
    char buffer[1024];
    result = recv(clientSocket, buffer, sizeof(buffer), 0);
    if (result == SOCKET_ERROR) {
        cout << "recv failed: " << WSAGetLastError() << endl;
        closesocket(clientSocket);
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    // 处理客户端发送的数据
    cout << "Received from client: " << buffer << endl;

    // 关闭socket
    closesocket(clientSocket);
    closesocket(listenSocket);
    WSACleanup();

    return 0;
}

客户端代码：

#include <iostream>
#include <winsock2.h>

using namespace std;

int main()
{
    // 初始化Winsock库
    WSADATA wsaData;
    int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (result != 0) {
        cout << "WSAStartup failed: " << result << endl;
        return 1;
    }

    // 创建socket
    SOCKET clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (clientSocket == INVALID_SOCKET) {
        cout << "socket failed: " << WSAGetLastError() << endl;
        WSACleanup();
        return 1;
    }

    // 连接服务器
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(12345);
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    result = connect(clientSocket, (sockaddr*)&serverAddr, sizeof(serverAddr));
    if (result == SOCKET_ERROR) {
        cout << "connect failed: " << WSAGetLastError() << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }

    // 发送数据到服务器
    const char* message = "Hello, server!";
    result = send(clientSocket, message, strlen(message), 0);
    if (result == SOCKET_ERROR) {
        cout << "send failed: " << WSAGetLastError() << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }

    // 关闭socket
    closesocket(clientSocket);
    WSACleanup();

    return 0;
}

在Windows环境下编译运行上述代码，即可实现简单的socket通讯。