Error 401 using curl in PHP to access REST API - php

Question

I am trying to execute a curl command that I can execute successfully in the terminal but it fails in PHP script with the following error:
HTTP/1.1 401 Unauthorized Access-Control-Allow-Origin: * Access-Control-Request-Method: * Cache-Control: no-cache Content-Type: application/json; charset=utf-8 Date: Mon, 06 Feb 2012 00:38:56 GMT Server: nginx/1.0.4 Set-Cookie: _parse_session=XXXXXX; domain=.parse.com; path=/; expires=Sun, 06-Feb-2022 00:38:56 GMT; HttpOnly Status: 401 Unauthorized WWW-Authenticate: Basic realm="Parse" X-Runtime: 0.002486 X-UA-Compatible: IE=Edge,chrome=1 Content-Length: 24 Connection: keep-alive {"error":"unauthorized"}
This is the command executed in terminal that executes successfully:
curl -H "Accept: application/json" -H "X-Parse-Application-Id: XXXXXXX" -H "X-Parse-REST-API-Key: XXXXXXXXX" -X GET "https://api.parse.com/1/classes/XXXXXX"
This is the PHP code:
$fields = array('Accept: '=>'application/json',
'X-Parse-Application-Id:' => 'XXXXX',
'X-Parse-REST-API-Key:' => 'XXXXX');
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://api.parse.com/1/classes/XXXX');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, false);
curl_setopt($ch, CURLOPT_HEADER, $fields);
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
curl_setopt(CURLOPT_USERPWD, 'XXXXXX');
$result = curl_exec($ch);
curl_close($ch);
The interesting note is that when executed in the terminal authentication info is not required.
Help will be appreciated.
Thanks

Answer 1

Your header fields shouldn't have the : in the array defnition:
'X-Parse-REST-API-Key:' => 'XXXXX');
^---remove these
That makes the : part of the field name, so you're actually sending:
X-Parse-REST-API-Key:: XXXXX
^^---note the doubled colons

Answer 2

Your header is set using CURLOPT_HTTPHEADER, not CURLOPT_HEADER which expects a boolean value