__autoload() is deprecated, use spl_autoload_register() instead

OLD CODE

function __autoload($class) {
    if (file_exists(APPPATH."core/".$class.'.php')) {
        include_once(APPPATH."core/".$class.'.php');
    }
}

NEW CODE

spl_autoload_register(function($class) {
   if (file_exists(APPPATH."core/".$class.'.php')) {
        include_once(APPPATH."core/".$class.'.php');
    }
});