It's super simple to download any accessible file from the internet when using libcurl. To download a file using curl in cpp, you can use the following code:

1. Include the curl library in your cpp file using the "#include" directive.

2. Initialize a curl handle using the "curl_easy_init" function.

3. Set the URL of the file to be downloaded using the "curl_easy_setopt" function and the CURLOPT_URL option.

4. Set the destination file path using the "curl_easy_setopt" function and the CURLOPT_WRITEFUNCTION and CURLOPT_WRITEDATA options.

5. Perform the download operation using the "curl_easy_perform" function.

6. Clean up the curl handle using the "curl_easy_cleanup" function.

For example:

#include <curl/curl.h>

int main(int argc, char** argv) {
  CURL *curl = curl_easy_init();
  if (curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/file.zip"); 
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, "file.zip"); curl_easy_perform(curl); 
    curl_easy_cleanup(curl);
  }
  return 0;
}