curl - Salesforce REST API with PHP, INVALID_SESSION_ID after successful authentication -

i connected web app salesforce , followed steps in web server oauth flow access_token , related info: https://developer.salesforce.com/docs/atlas.en-us.api_placeorder.meta/api_placeorder/intro_understanding_web_server_oauth_flow.htm

every step seems return expected set of results specified in docs, when try make requests final access token, error saying session id invalid. here code:

    // execute request access_token , related info     $output = json_decode(curl_exec($ch));     curl_close($ch);     var_dump($output);      // extract token , instance_url output     $sf_url = $output->instance_url . '/services/data/v35.0/';     $sf_auth = 'bearer ' . $output->access_token;      // execute new curl request auth values     $ci = curl_init();     curl_setopt($ci, curlopt_url, $sf_url);     curl_setopt($ci, curlopt_returntransfer, true);     curl_setopt($ci, curlopt_httpheader, array(         'accept' => '*/*',         'authorization' => $sf_auth,         'x-prettyprint' => 1     ));      $output2 = curl_exec($ci);     curl_close($ci);     var_dump($output2); 

the dump $output gives:

object(stdclass)#194 (7) {  ["access_token"]=> string(112) "xxxxxxxxxxxxxxxx"  ["signature"]=> string(44) "xxxxxxxxxxxxxx"  ["scope"]=> string(3) "api"  ["instance_url"]=> string(27) "https://cs10.salesforce.com"  ["id"]=> string(68) "https://test.salesforce.com/id/xxxxx/xxxxx" ["token_type"]=> string(6) "bearer"  ["issued_at"]=> string(13) "1453358xxxxxx" } 

the dump $output2 gives:

string(75) "[{"message":"session expired or invalid","errorcode":"invalid_session_id"}]" 

any here appreciated.

* update *

i tried using username-password auth flow, , i'm getting same result. can access token, can't query database, , error being returned same invalid_session_id.

i used postman plugin chrome, passed in same info username-password flow, , works making queries. i'm not sure being done differently, seems data being passed same.

i found answer, had wrong syntax setting curl headers. tried pass values associative array, correct way this:

curl_setopt($ci, curlopt_httpheader, array(     'accept: application/json',     'authorization:' . $sf_auth,     'x-prettyprint:1' ));