CURLOPT_WRITEFUNCTION

CURLOPT_WRITEFUNCTION is one of the accepted parameters for curl_setopt parameter #2.

CURLOPT_WRITEFUNCTION — A callable with the following signature:

 The data must be saved by the callback
 and the callback must return the exact number of bytes written
 or the transfer will be aborted with an error.
 Available as of cURL 7.1.0.

CURLOPT_WRITEFUNCTION = 20011;