以下是一个简单的C++ TCP 服务端和客户端通信的例子，针对 Windows 环境：

服务器端代码（server.cpp）：

#include <iostream>
#include <winsock2.h>
#include <Ws2tcpip.h> // for inet_ntop#pragma comment(lib, "Ws2_32.lib")#define PORT 8080int main() {WSADATA wsaData;SOCKET serverSocket, newSocket;struct sockaddr_in serverAddr, clientAddr;int clientAddrLen = sizeof(clientAddr);char buffer[1024] = { 0 };const char* message = "Hello from server";// 初始化 Winsockif (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {std::cerr << "WSAStartup failed." << std::endl;return 1;}// 创建服务器套接字if ((serverSocket = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {std::cerr << "Socket creation failed." << std::endl;WSACleanup();return 1;}// 设置服务器地址serverAddr.sin_family = AF_INET;serverAddr.sin_addr.s_addr = INADDR_ANY;serverAddr.sin_port = htons(PORT);// 将套接字绑定到服务器地址if (bind(serverSocket, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {std::cerr << "Bind failed." << std::endl;closesocket(serverSocket);WSACleanup();return 1;}// 监听连接if (listen(serverSocket, 5) == SOCKET_ERROR) {std::cerr << "Listen failed." << std::endl;closesocket(serverSocket);WSACleanup();return 1;}std::cout << "Server listening on port " << PORT << std::endl;// 接受客户端连接if ((newSocket = accept(serverSocket, (struct sockaddr*)&clientAddr, &clientAddrLen)) == INVALID_SOCKET) {std::cerr << "Accept failed." << std::endl;closesocket(serverSocket);WSACleanup();return 1;}// Convert client IP address to stringchar clientIP[INET_ADDRSTRLEN];inet_ntop(AF_INET, &clientAddr.sin_addr, clientIP, INET_ADDRSTRLEN);std::cout << "Connection accepted from " << clientIP << ":" << ntohs(clientAddr.sin_port) << std::endl;// 从客户端接收消息int valread;if ((valread = recv(newSocket, buffer, sizeof(buffer), 0)) == SOCKET_ERROR) {std::cerr << "Recv failed." << std::endl;closesocket(newSocket);closesocket(serverSocket);WSACleanup();return 1;}if (valread == 0) {std::cout << "Client disconnected." << std::endl;}else {std::cout << "Message from client: " << buffer << std::endl;}// 发送消息到客户端if (send(newSocket, message, strlen(message), 0) == SOCKET_ERROR) {std::cerr << "Send failed." << std::endl;closesocket(newSocket);closesocket(serverSocket);WSACleanup();return 1;}std::cout << "Message sent to client." << std::endl;// 关闭套接字closesocket(newSocket);closesocket(serverSocket);WSACleanup();return 0;
}

客户端代码（client.cpp）：

#include <iostream>
#include <winsock2.h>
#include <Ws2tcpip.h> // for inet_pton#pragma comment(lib, "Ws2_32.lib")#define PORT 8080
#define SERVER_IP "127.0.0.1"int main() {WSADATA wsaData;SOCKET clientSocket;struct sockaddr_in serverAddr;char buffer[1024] = { 0 };const char* message = "Hello from client";// 初始化 Winsockif (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {std::cerr << "WSAStartup failed." << std::endl;return 1;}// 创建客户端套接字if ((clientSocket = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {std::cerr << "Socket creation failed." << std::endl;WSACleanup();return 1;}// 设置服务器地址serverAddr.sin_family = AF_INET;inet_pton(AF_INET, SERVER_IP, &(serverAddr.sin_addr));serverAddr.sin_port = htons(PORT);// 连接到服务器if (connect(clientSocket, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {std::cerr << "Connect failed." << std::endl;closesocket(clientSocket);WSACleanup();return 1;}std::cout << "Connected to server." << std::endl;// 发送消息到服务器if (send(clientSocket, message, strlen(message), 0) == SOCKET_ERROR) {std::cerr << "Send failed." << std::endl;closesocket(clientSocket);WSACleanup();return 1;}std::cout << "Message sent to server." << std::endl;// 接收来自服务器的消息int valread;if ((valread = recv(clientSocket, buffer, sizeof(buffer), 0)) == SOCKET_ERROR) {std::cerr << "Recv failed." << std::endl;closesocket(clientSocket);WSACleanup();return 1;}if (valread == 0) {std::cout << "Server disconnected." << std::endl;}else {std::cout << "Message from server: " << buffer << std::endl;}// 关闭套接字closesocket(clientSocket);WSACleanup();return 0;
}

这个例子中，服务器端和客户端之间通过 TCP 进行通信。服务器监听端口8080，并等待客户端连接。一旦有客户端连接进来，服务器端会接收来自客户端的消息，然后向客户端发送一条消息。客户端首先连接到服务器，然后发送一条消息给服务器，然后从服务器接收一条消息。

TCP 服务端与客户端通信的流程如下：

1. 初始化 Winsock 库。
2. 服务器创建套接字并绑定到特定的 IP 地址和端口上。
3. 服务器监听来自客户端的连接请求。
4. 客户端创建套接字并连接到服务器的 IP 地址和端口。
5. 服务器接受客户端连接请求，建立连接。
6. 客户端向服务器发送数据。
7. 服务器接收来自客户端的数据。
8. 服务器向客户端发送响应数据。

客户端接收来自服务器的响应数据。
10. 连接关闭或其他操作。