3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = []; print $a['hello'] ?? 'world'; print "\n";
Output for 7.4.0 - 7.4.30, 8.0.1 - 8.0.20, 8.1.0 - 8.1.7
world

preferences:
24.77 ms | 409 KiB | 5 Q