Simple curl download example

main.cpp

#include <iostream>
#include <fstream>
#include <curl/curl.h>
// g++ -o test test.cpp -lcurl

// Callback function to write data to a file
size_t WriteCallback(void* contents, size_t size, size_t nmemb, void* userp)
{
    size_t totalSize = size * nmemb;
    std::ofstream* fileStream = static_cast<std::ofstream*>(userp);
    if (fileStream)
    {
        fileStream->write(static_cast<const char*>(contents), totalSize);
        return totalSize;
    }
    return 0;
}

int main()
{
    CURL* curl;
    CURLcode res;

    // URL to download
    const char* url = "https://caret.rs/";

    // Output file name
    const char* outputFile = "downloaded.html";

    // Initialize libcurl
    curl_global_init(CURL_GLOBAL_DEFAULT);
    curl = curl_easy_init();

    if (curl)
    {
        // Create or open a file to write the downloaded data
        std::ofstream file(outputFile, std::ios::binary);

        // Set the URL to download
        curl_easy_setopt(curl, CURLOPT_URL, url);

        // Set the callback function to write data to the file
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &file);

        // Perform the HTTP request and download
        res = curl_easy_perform(curl);

        // Check for errors
        if (res != CURLE_OK)
        {
            std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
        }
        else
        {
            std::cout << "Download successful." << std::endl;
        }

        // Clean up
        curl_easy_cleanup(curl);
        file.close();
    }

    // Cleanup libcurl
    curl_global_cleanup();

    return 0;
}