3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = [1, 2]; $a[] = &$b; $b = 4; print_r($a);
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
Array ( [0] => 1 [1] => 2 [2] => 4 )
preferences:
92.17 ms | 402 KiB | 91 Q