accesings protected variable in php : I have created protected variable in php and want to use in php function within same class.I have printed `$program_owner_id` 

> Undefined variable: project_owner_id

 
 <?php
  class userController extends Controller
  {
   protected $program_owner_id = array (); //protected variable
     public function mappingUserToRequest() {
          print_r($program_owner_id)  /Expected to use here
     }

  }
  ?>