FTP 编写 2：客户端与服务端的连接

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    首先编写客户端与服务端能进行简单的连接，这个较为容易：

    服务端的编写流程是：启动 Winsock、建立套接字、绑定套接字、监听、接收连接、关闭连接、关闭套接字、关闭 Winsock

    客户端的编写流程是：启动 Winsock、建立套接字、连接、关闭连接和套接字、关闭 Winsock

    代码较为简单，具体如下：

服务端

#include <Winsock2.h>#include <Ws2tcpip.h>#include <iostream>#pragma comment(lib,"ws2_32.lib")void main(){    //定义相关的数据    int iPort = 5050;//定义其端口    WSADATA wsaData;//Winsock 的启动参数    SOCKET sListen, sAccept;//套接口关键字,分别用于监听和接收连接    int iLen;    int iSend;    char buf[] = "I am a server";    struct sockaddr_in ser, cli;//网络地址    std::cout << "----------------------------\n";    std::cout << "Server waitting\n";    std::cout << "----------------------------\n";    //启动winSocket    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {        std::cout << "Failed to load Winsock.\n";        return;    }    //创建Socket    sListen = socket(AF_INET, SOCK_STREAM, 0);    if (sListen == INVALID_SOCKET) {        std::cout << "socket() Failed:" << WSAGetLastError() <<"\n";        return;    }    //绑定IP地址    ser.sin_family = AF_INET;    ser.sin_port = htons(iPort);    ser.sin_addr.s_addr = htonl(INADDR_ANY);    if (bind(sListen, (LPSOCKADDR)&ser, sizeof(ser)) == SOCKET_ERROR) {        std::cout << "bind() Failed\n";        return;    }    //监听    if (listen(sListen, 5) == SOCKET_ERROR) {        std::cout << "listen() Failed\n";        return;    }    iLen = sizeof(cli);//获取客户端网络地址的长度    //接受连接和发送欢迎信息    //用循环使程序一直运行    while (true) {        //接收连接        sAccept = accept(sListen, (struct sockaddr*)&cli, &iLen);        if (sAccept == INVALID_SOCKET) {            std::cout << "accept() Failed\n";            break;        }        //显示客户端的 IP 信息        char clibuf[20] = { '\0' };        inet_ntop(AF_INET, (void*)&cli.sin_addr, clibuf, 16);        std::cout << "Accept client IP:" << clibuf << ":" << ntohs(cli.sin_port) << std::endl;        //发送信息给客户端        iSend = send(sAccept, buf, sizeof(buf), 0);        if (iSend == SOCKET_ERROR) {            std::cout << "send() Failed\n";            break;        }        else if (iSend == 0) {            break;        }        else {            std::cout << "Send byte:" << iSend << std::endl;            std::cout << "----------------------------------\n";        }        //关闭连接        closesocket(sAccept);    }    //关闭监听    closesocket(sListen);    //关闭 Winsock    WSACleanup();}

客户端

#include <Winsock2.h>#include <WS2tcpip.h>#include <iostream>#pragma comment(lib,"ws2_32.lib")void main(){    //定义相应的数据    WSADATA wsaData;    SOCKET sClient;    int iPort = 5050;//对应的服务端的端口    int iLen;    char buf[1024];    struct sockaddr_in ser;    //启动 winSocket    memset(buf, 0, sizeof(buf));    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {        std::cout << "Failed to load Winsock\n";        system("pause");        return;    }    char addr[20] = { '\0' };    std::cin >> addr;//输入服务端 IP 地址    //创建Socket    ser.sin_family = AF_INET;    ser.sin_port = htons(iPort);    inet_pton(AF_INET, addr, (void*)&ser.sin_addr.s_addr);    sClient = socket(AF_INET, SOCK_STREAM, 0);    if (sClient == INVALID_SOCKET) {        std::cout << "socket() Failed\n";        system("pause");        return;    }    //连接并进行简单的操作    if (connect(sClient, (struct sockaddr*)&ser, sizeof(ser)) == INVALID_SOCKET) {        std::cout << "connect() Failed\n";        system("pause");        return;    }    else {        //接收服务端发送的数据        iLen = recv(sClient, buf, sizeof(buf), 0);        if (iLen == 0) {            system("pause");            return;        }        else if (iLen == SOCKET_ERROR) {            std::cout << "recv() Failed\n";            system("pause");            return;        }        std::cout << "recv() data from server:" << buf << std::endl;    }    //关闭连接并退出    closesocket(sClient);    //关闭 Winsock    WSACleanup();    system("pause");}

启动运行

    需要注意的是在客户端输入的 IP 地址，这个地址需要输入本地电脑的 IP 地址，使用 cmd 调出 Windows 的 DOS 界面，输入 ipconfig 命令，找到 IPv4 地址，然后在 客户端进行填写即可