- var_dump: documentation ( source)
- error_reporting: documentation ( source)
<?php
error_reporting(E_ALL);
echo $_GET['aaa'];
$user = $_GET['xxx'] ?? 'nobody';
var_dump($user);
$null = '';
var_dump($null??'haha');
$arr = ['a' => 1];
echo $arr[0];
var_dump($arr['b'] ?? 'bbbb');