Runtime C++ Download |verified| File

int DownloadManager::progressCallback(void* userp, curl_off_t dltotal, curl_off_t dlnow, curl_off_t ultotal, curl_off_t ulnow) auto* ctx = static_cast<DownloadContext*>(userp); if (dltotal > 0) ctx->total_bytes = dltotal; if (ctx->progress_cb) float progress = (float)dlnow / dltotal; ctx->progress_cb(progress, dlnow, dltotal); return 0; // Return non-zero to cancel

class DownloadManager public: using ProgressCallback = std::function<void(float progress, size_t downloaded, size_t total)>; using CompleteCallback = std::function<void(bool success, const std::string& error)>; struct DownloadOptions std::string url; std::string output_path; int timeout_seconds = 30; int max_retries = 3; bool resume_on_failure = true; std::string username; // Optional for auth std::string password; // Optional for auth std::string user_agent = "C++DownloadManager/1.0"; ; DownloadManager(); ~DownloadManager(); // Start async download void downloadAsync(const DownloadOptions& options, ProgressCallback progress = nullptr, CompleteCallback complete = nullptr); // Sync download with progress bool downloadSync(const DownloadOptions& options, ProgressCallback progress = nullptr); // Cancel active download void cancel(); // Check if download is active bool isActive() const return m_active; // Get last error std::string getLastError() const return m_lastError;

int main() DownloadManager dm; DownloadManager::DownloadOptions options; options.url = "https://example.com/file.zip"; options.output_path = "downloaded_file.zip"; options.max_retries = 2; options.resume_on_failure = true; std::cout << "Starting download..." << std::endl; auto start_time = std::chrono::steady_clock::now(); // Async download with callbacks dm.downloadAsync(options, // Progress callback [](float progress, size_t downloaded, size_t total) std::cout << "\rProgress: " << (progress * 100) << "% (" << downloaded << "/" << total << " bytes)" << std::flush; , // Complete callback [&start_time](bool success, const std::string& error) auto end_time = std::chrono::steady_clock::now(); auto duration = std::chrono::duration_cast<std::chrono::seconds>(end_time - start_time); if (success) std::cout << "\nDownload completed in " << duration.count() << " seconds!" << std::endl; else std::cout << "\nDownload failed: " << error << std::endl; ); // Wait for completion while (dm.isActive()) std::this_thread::sleep_for(std::chrono::milliseconds(100)); return 0; runtime c++ download

cmake_minimum_required(VERSION 3.10) project(DownloadManager) set(CMAKE_CXX_STANDARD 17)

This is production-ready code that handles real-world download scenarios efficiently. int DownloadManager::progressCallback(void* userp

DownloadManager::~DownloadManager() cancel(); if (m_downloadThread.joinable()) m_downloadThread.join(); if (m_curl) curl_easy_cleanup(m_curl); curl_global_cleanup();

// Helper: Get file size size_t getFileSize(const std::string& path) struct stat stat_buf; if (stat(path.c_str(), &stat_buf) == 0) return stat_buf.st_size; return 0; curl_off_t ulnow) auto* ctx = static_cast&lt

void DownloadManager::cancel() m_cancel = true; if (m_downloadThread.joinable()) m_downloadThread.join();