c++ 编写socket

在 C++ 中编写 Socket 程序需要使用到 socket 编程库，如 Winsock、Berkeley sockets 等。以下是一个简单的使用 Winsock 编写的服务器端和客户端的示例：

服务器端代码：

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

#pragma comment(lib,"ws2_32.lib")

int main() {
    WSADATA wsaData;
    SOCKET serverSocket, clientSocket;
    sockaddr_in serverAddr, clientAddr;
    int serverPort = 8888;
    char buffer[1024];
    
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        std::cout << "WSAStartup failed!" << std::endl;
        return -1;
    }
    
    serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serverSocket == INVALID_SOCKET) {
        std::cout << "socket failed!" << std::endl;
        WSACleanup();
        return -1;
    }
    
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(serverPort);
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    
    if (bind(serverSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {
        std::cout << "bind failed!" << std::endl;
        closesocket(serverSocket);
        WSACleanup();
        return -1;
    }
    
    if (listen(serverSocket, SOMAXCONN) == SOCKET_ERROR) {
        std::cout << "listen failed!" << std::endl;
        closesocket(serverSocket);
        WSACleanup();
        return -1;
    }
    
    std::cout << "Server is listening on port " << serverPort << std::endl;
    
    while (true) {
        int clientAddrLen = sizeof(clientAddr);
        clientSocket = accept(serverSocket, (sockaddr*)&clientAddr, &clientAddrLen);
        if (clientSocket == INVALID_SOCKET) {
            std::cout << "accept failed!" << std::endl;
            closesocket(serverSocket);
            WSACleanup();
            return -1;
        }
        
        std::cout << "Client connected: " << inet_ntoa(clientAddr.sin_addr) << std::endl;
        
        while (true) {
            memset(buffer, 0, sizeof(buffer));
            int recvBytes = recv(clientSocket, buffer, sizeof(buffer), 0);
            if (recvBytes == SOCKET_ERROR) {
                std::cout << "recv failed!" << std::endl;
                closesocket(clientSocket);
                WSACleanup();
                return -1;
            }
            else if (recvBytes == 0) {
                std::cout << "Client disconnected: " << inet_ntoa(clientAddr.sin_addr) << std::endl;
                break;
            }
            
            std::cout << "Received data from client: " << buffer << std::endl;
            
            int sendBytes = send(clientSocket, buffer, recvBytes, 0);
            if (sendBytes == SOCKET_ERROR) {
                std::cout << "send failed!" << std::endl;
                closesocket(clientSocket);
                WSACleanup();
                return -1;
            }
        }
        
        closesocket(clientSocket);
    }
    
    closesocket(serverSocket);
    WSACleanup();
    
    return 0;
}

客户端代码：

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

#pragma comment(lib,"ws2_32.lib")

int main() {
    WSADATA wsaData;
    SOCKET clientSocket;
    sockaddr_in serverAddr;
    char buffer[1024];
    
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        std::cout << "WSAStartup failed!" << std::endl;
        return -1;
    }
    
    clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (clientSocket == INVALID_SOCKET) {
        std::cout << "socket failed!" << std::endl;
        WSACleanup();
        return -1;
    }
    
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(8888);
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    
    if (connect(clientSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {
        std::cout << "connect failed!" << std::endl;
        closesocket(clientSocket);
        WSACleanup();
        return -1;
    }
    
    std::cout << "Connected to server!" << std::endl;
    
    while (true) {
        std::cout << "Please input data to send: ";
        std::cin.getline(buffer, sizeof(buffer));
        if (strcmp(buffer, "exit") == 0) {
            break;
        }
        
        int sendBytes = send(clientSocket, buffer, strlen(buffer), 0);
        if (sendBytes == SOCKET_ERROR) {
            std::cout << "send failed!" << std::endl;
            closesocket(clientSocket);
            WSACleanup();
            return -1;
        }
        
        memset(buffer, 0, sizeof(buffer));
        int recvBytes = recv(clientSocket, buffer, sizeof(buffer), 0);
        if (recvBytes == SOCKET_ERROR) {
            std::cout << "recv failed!" << std::endl;
            closesocket(clientSocket);
            WSACleanup();
            return -1;
        }
        
        std::cout << "Received data from server: " << buffer << std::endl;
    }
    
    closesocket(clientSocket);
    WSACleanup();
    
    return 0;
}