vs2019 socket tcp客户端连接代码

以下是一个基本的TCP客户端连接代码示例，使用Visual Studio 2019和C++编写。

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

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

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

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

    // 填写服务器地址和端口号
    sockaddr_in serverAddress;
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_addr.s_addr = inet_addr("127.0.0.1"); // 服务器IP地址
    serverAddress.sin_port = htons(12345); // 服务器端口号

    // 连接服务器
    result = connect(clientSocket, (SOCKADDR*)&serverAddress, sizeof(serverAddress));
    if (result == SOCKET_ERROR) {
        std::cout << "Failed to connect to server: " << WSAGetLastError() << std::endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }

    // 连接成功，可以进行通信了
    char buffer[1024];
    result = recv(clientSocket, buffer, sizeof(buffer), 0);
    if (result == SOCKET_ERROR) {
        std::cout << "Failed to receive data from server: " << WSAGetLastError() << std::endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    buffer[result] = '\0';
    std::cout << "Received message from server: " << buffer << std::endl;

    // 关闭socket，释放资源
    closesocket(clientSocket);
    WSACleanup();

    return 0;
}

此代码使用Windows套接字API来创建一个TCP客户端，连接到指定的服务器地址和端口。如果连接成功，则从服务器接收数据并在控制台上输出。最后，关闭套接字和清理资源。注意在使用Windows套接字API时需要调用`WSAStartup()`和`WSACleanup()`函数来初始化和释放Winsock库。