Online PHP editor | output for WBIPe

<?php $users = [ 1 => 'Hello World' ]; $_SESSION['user_id'] = 'ABC'; if (\array_key_exists('user_id', $_SESSION) && $user_id = \filter_var($_SESSION['user_id'], \FILTER_VALIDATE_INT)) { //not executed $user = $users[$user_id]; var_dump($user); } $_SESSION['user_id'] = '1'; if (\array_key_exists('user_id', $_SESSION) && $user_id = \filter_var($_SESSION['user_id'], \FILTER_VALIDATE_INT)) { $user = $users[$user_id]; var_dump($user); } $_SESSION['user_id'] = 'ABC'; if (!empty($_SESSION['user_id'])) { $user_id = $_SESSION['user_id']; $user = $users[$user_id]; //error var_dump($user); //null }