用c++和ws2-32库写一个聊天室服务端

好的，以下是一个简单的聊天室服务端的C++代码：

#include <iostream>
#include <winsock2.h> //ws2_32库头文件
#pragma comment(lib,"ws2_32.lib") //ws2_32库链接

using namespace std;

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

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

    //绑定端口
    sockaddr_in service;
    service.sin_family = AF_INET;
    service.sin_addr.s_addr = INADDR_ANY;
    service.sin_port = htons(1234);
    iResult = bind(listenSocket, (SOCKADDR*)&service, sizeof(service));
    if (iResult == SOCKET_ERROR) {
        cout << "bind failed: " << WSAGetLastError() << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

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

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

    cout << "Client connected: " << inet_ntoa(clientAddr.sin_addr) << endl;

    //接收客户端消息
    char recvbuf[1024];
    int recvbuflen = 1024;
    iResult = recv(clientSocket, recvbuf, recvbuflen, 0);
    if (iResult > 0) {
        cout << "Received: " << recvbuf << endl;
    }
    else if (iResult == 0) {
        cout << "Connection closing..." << endl;
    }
    else {
        cout << "recv failed: " << WSAGetLastError() << endl;
        closesocket(clientSocket);
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    //发送消息给客户端
    const char* sendbuf = "Welcome to the chat room!";
    int sendbuflen = strlen(sendbuf);
    iResult = send(clientSocket, sendbuf, sendbuflen, 0);
    if (iResult == SOCKET_ERROR) {
        cout << "send failed: " << WSAGetLastError() << endl;
        closesocket(clientSocket);
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

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

    return 0;
}

注意事项：
1. 该代码只支持单个客户端连接，若要支持多个客户端，则需要用多线程等技术进行改进。
2. 要在Windows系统上编译运行该代码，需要使用Visual Studio等IDE，并在项目属性中添加ws2_32.lib库链接。