我帮你排查了这段基于微软官方文档的WinSock客户端代码，发现了几个关键问题，这应该就是你无法成功运行的原因：

1. 端口参数未正确传入getaddrinfo #

你已经定义了DEFAULT_PORT为目标端口"27015"，但调用getaddrinfo时第二个端口参数传了NULL，这会导致地址解析时没有包含端口信息，后续的connect调用自然无法找到正确的服务端口。

修复方法：把getaddrinfo调用中的NULL替换为DEFAULT_PORT：

iResult = getaddrinfo("127.0.0.1", DEFAULT_PORT, &hints, &result);

2. 确保目标服务器正在运行 #

客户端要连接的是127.0.0.1:27015的TCP服务，如果没有对应的服务器程序在这个端口监听，connect必然会失败。你可以：

• 运行微软官方配套的WinSock服务器示例代码
• 自己写一个简单的TCP监听程序测试，或者用工具在本地27015端口开启监听

3. 可选的代码优化与调试点 #

除了功能性问题，还有几个可以优化的地方，方便你后续调试：

• 将#define DEFAULT_BUFLEN和#define DEFAULT_PORT移到main函数外面，避免局部宏定义的潜在问题，符合C/C++代码规范
• 在recv成功后，添加代码打印收到的实际内容（记得给缓冲区加终止符避免乱码），方便验证通信是否正常：

if (iResult > 0) {
    printf("Bytes received: %d\n", iResult);
    recvbuf[iResult] = '\0'; // 添加终止符
    printf("Received content: %s\n", recvbuf);
}

修改后的完整代码片段（关键部分已修正） #

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include "stdafx.h"
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#pragma comment(lib, "Ws2_32.lib")

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"

int main() {
    WSADATA wsaData;

    SOCKET ConnectSocket = INVALID_SOCKET;
    struct addrinfo *result = NULL, *ptr = NULL, hints;
    char *sendbuf = "this is a test";
    char recvbuf[DEFAULT_BUFLEN];
    int iResult;
    int recvbuflen = DEFAULT_BUFLEN;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    // Resolve the server address and port - 已修复端口参数
    iResult = getaddrinfo("127.0.0.1", DEFAULT_PORT, &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // Attempt to connect to an address until one succeeds
    for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {
        // Create a SOCKET for connecting to server
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            printf("socket failed with error: %ld\n", WSAGetLastError());
            WSACleanup();
            return 1;
        }

        // Connect to server.
        iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);

    if (ConnectSocket == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }

    // Send an initial buffer
    iResult = send(ConnectSocket, sendbuf, (int)strlen(sendbuf), 0);
    if (iResult == SOCKET_ERROR) {
        printf("send failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    printf("Bytes Sent: %ld\n", iResult);

    // shutdown the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    // Receive until the peer closes the connection - 已添加内容打印
    do {
        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if (iResult > 0) {
            printf("Bytes received: %d\n", iResult);
            recvbuf[iResult] = '\0';
            printf("Received content: %s\n", recvbuf);
        }
        else if (iResult == 0)
            printf("Connection closed\n");
        else
            printf("recv failed with error: %d\n", WSAGetLastError());
    } while (iResult > 0);

    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();
    getchar();
    return 0;
}

内容的提问来源于stack exchange，提问作者qtjCH5pLao6