3v4l.org

run code in 300+ PHP versions simultaneously
<?php class A { public $b; } $a = new A; $a->b = new A; $a->b->b = null; if (isset($a->b->b)) { echo 'exists'; }
Output for 7.2.29 - 7.2.33, 7.3.16 - 7.3.33, 7.4.4 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4

preferences:
132.32 ms | 403 KiB | 131 Q