如何在cUrl C++中实现Ftp Get in Memory函数？

#include <iostream>
#include <curl/curl.h>

// 回调函数，用于接收FTP响应数据
size_t WriteMemoryCallback(void* contents, size_t size, size_t nmemb, std::string* buffer) {
    size_t totalSize = size * nmemb;
    buffer->append(static_cast<char*>(contents), totalSize);
    return totalSize;
}

// Ftp Get in Memory函数
std::string FtpGetInMemory(const std::string& url) {
    std::string response;

    // 初始化cURL
    curl_global_init(CURL_GLOBAL_DEFAULT);

    // 创建cURL句柄
    CURL* curl = curl_easy_init();
    if (curl) {
        // 设置FTP URL
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());

        // 设置回调函数
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response);

        // 执行FTP请求
        CURLcode res = curl_easy_perform(curl);
        if (res != CURLE_OK) {
            std::cerr << "FTP request failed: " << curl_easy_strerror(res) << std::endl;
        }

        // 清理cURL句柄
        curl_easy_cleanup(curl);
    }

    // 清理cURL
    curl_global_cleanup();

    return response;
}

int main() {
    std::string url = "ftp://example.com/file.txt";
    std::string result = FtpGetInMemory(url);
    std::cout << "FTP response: " << result << std::endl;

    return 0;
}