用c++进行套接字编程，实现如下功能：实现一个FTP协议的客户端和服务端，完成基本的文件传输功能。Windows平台下只能使用Winsock(winsock.h)，请勿使用其它高层封装的Socket库。

好的，我理解你的需求。下面是使用C++编写基于FTP协议的客户端和服务端的示例代码。

首先是FTP服务器端的代码：

#include <iostream>
#include <string>
#include <fstream>
#include <winsock.h>

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

#define MAX_BUFFER_SIZE 1024
#define PORT 21

void SendFile(SOCKET clientSocket, const std::string& filename) {
    std::ifstream file(filename, std::ios::binary);
    if (!file) {
        std::cout << "Error opening file: " << filename << std::endl;
        return;
    }

    char buffer[MAX_BUFFER_SIZE];
    memset(buffer, 0, sizeof(buffer));
    
    while (!file.eof()) {
        file.read(buffer, sizeof(buffer));
        int bytesRead = file.gcount();
        send(clientSocket, buffer, bytesRead, 0);
        memset(buffer, 0, sizeof(buffer));
    }

    file.close();
}

int main() {
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        std::cout << "Failed to initialize winsock!" << std::endl;
        return -1;
    }

    SOCKET listenSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (listenSocket == INVALID_SOCKET) {
        std::cout << "Failed to create socket!" << std::endl;
        return -1;
    }

    sockaddr_in serverAddress{};
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_addr.s_addr = INADDR_ANY;
    serverAddress.sin_port = htons(PORT);

    if (bind(listenSocket, (sockaddr*)&serverAddress, sizeof(serverAddress)) == SOCKET_ERROR) {
        std::cout << "Failed to bind socket!" << std::endl;
        closesocket(listenSocket);
        return -1;
    }

    if (listen(listenSocket, SOMAXCONN) == SOCKET_ERROR) {
        std::cout << "Error listening on socket!" << std::endl;
        closesocket(listenSocket);
        return -1;
    }

    std::cout << "FTP Server started and listening on port " << PORT << std::endl;

    while (true) {
        sockaddr_in clientAddress{};
        int clientAddressSize = sizeof(clientAddress);

        SOCKET clientSocket = accept(listenSocket, (sockaddr*)&clientAddress, &clientAddressSize);
        if (clientSocket == INVALID_SOCKET) {
            std::cout << "Error accepting client connection!" << std::endl;
            closesocket(listenSocket);
            WSACleanup();
            return -1;
        }

        char clientIP[INET_ADDRSTRLEN];
        inet_ntop(AF_INET, &(clientAddress.sin_addr), clientIP, INET_ADDRSTRLEN);
        std::cout << "Accepted connection from " << clientIP << ":" << ntohs(clientAddress.sin_port) << std::endl;

        char buffer[MAX_BUFFER_SIZE];
        memset(buffer, 0, sizeof(buffer));
        
        recv(clientSocket, buffer, sizeof(buffer), 0);
        
        if (strcmp(buffer, "get") == 0) {
            std::string filename;
            recv(clientSocket, buffer, sizeof(buffer), 0);
            filename = buffer;

            SendFile(clientSocket, filename);
        }

        closesocket(clientSocket);
    }

    closesocket(listenSocket);
    WSACleanup();

    return 0;
}

接下来是FTP客户端的代码：

#include <iostream>
#include <string>
#include <fstream>
#include <winsock.h>

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

#define MAX_BUFFER_SIZE 1024
#define SERVER_IP "127.0.0.1"
#define PORT 21

void ReceiveFile(SOCKET clientSocket, const std::string& filename) {
    std::ofstream file(filename, std::ios::binary);
    if (!file) {
        std::cout << "Error creating file: " << filename << std::endl;
        return;
    }

    char buffer[MAX_BUFFER_SIZE];
    memset(buffer, 0, sizeof(buffer));

    int bytesRead;
    while ((bytesRead = recv(clientSocket, buffer, sizeof(buffer), 0)) > 0) {
        file.write(buffer, bytesRead);
        memset(buffer, 0, sizeof(buffer));
    }

    file.close();
}

int main() {
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        std::cout << "Failed to initialize winsock!" << std::endl;
        return -1;
    }

    SOCKET clientSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (clientSocket == INVALID_SOCKET) {
        std::cout << "Failed to create socket!" << std::endl;
        WSACleanup();
        return -1;
    }

    sockaddr_in serverAddress{};
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_port = htons(PORT);
    inet_pton(AF_INET, SERVER_IP, &(serverAddress.sin_addr));

    if (connect(clientSocket, (sockaddr*)&serverAddress, sizeof(serverAddress)) == SOCKET_ERROR) {
        std::cout << "Failed to connect to server!" << std::endl;
        closesocket(clientSocket);
        WSACleanup();
        return -1;
    }

    std::cout << "Connected to FTP server at " << SERVER_IP << ":" << PORT << std::endl;

    std::string command;
    std::cout << "Enter command (get <filename>): ";
    std::getline(std::cin, command);

    send(clientSocket, command.c_str(), command.size(), 0);

    if (command.substr(0, 3) == "get") {
        std::string filename = command.substr(4);
        ReceiveFile(clientSocket, filename);
        std::cout << "File " << filename << " received from server." << std::endl;
    }

    closesocket(clientSocket);
    WSACleanup();

    return 0;
}

请注意，这只是一个简单的示例代码，没有进行错误处理和安全性检查。在实际使用中，需要进一步完善代码以满足实际需求。

希望对你有所帮助！如果有任何其他问题，请随时问我。