Question

I’ve created a program that downloads subtitles from INTERNET using curl
How to know the extension of the file I downloaded (.zip or .rar)?

here is my code (it is a part of function)

FILE* download=fopen("download.zip","wb");//i assume it's a zip
curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_POST,1);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS,post_data.c_str());
curl_easy_setopt(curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)");
curl_easy_setopt(curl, CURLOPT_URL,url.c_str());
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write2file);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, download);
res = curl_easy_perform(curl);
if(res != CURLE_OK)
    std::cout<<"Download Failed "<<std::endl;
curl_easy_cleanup(curl);
fclose(download);

Answer 1

You can use the curl_easy_getinfo() function, it has the content-type info:

CURLINFO_CONTENT_TYPE

Pass a pointer to a char pointer to receive the content-type of the
downloaded object. This is the value read from the Content-Type:
field. If you get NULL, it means that the server didn’t send a valid
Content-Type header or that the protocol used doesn’t support this.

Using the info you can give the right extension to the downloaded file by renaming it on disk.