3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a=[1]; $a[]=&$a; print_r($a);
Output for 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
Array ( [0] => 1 [1] => Array *RECURSION* )
preferences:
152.4 ms | 407 KiB | 5 Q