Why need you use Expect: 100-continue when sending big data?
When we post big data (big file) to web serve with php curl, we may encounter problem:empty replay from server, At that situation, you should use Expect: 100-continue.
How to use Expect: 100-continue?
Expect: 100-continue is a http request header, You can check how to send a http request at PHP send request header to server. If you want post a big data with it, you can do like this:
<?php curl_setopt($ch, CURLOPT_HTTPHEADER, array('Expect:')); ?>