3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array(); $a[] = &$a; var_dump($a); print_r($a);
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
array(1) { [0]=> *RECURSION* } Array ( [0] => Array *RECURSION* )
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
array(1) { [0]=> &array(1) { [0]=> *RECURSION* } } Array ( [0] => Array *RECURSION* )
Output for 5.5.0 - 5.5.38, 5.6.0 - 5.6.40
array(1) { [0]=> &array(1) { [0]=> *RECURSION* } } Array ( [0] => Array ( [0] => Array *RECURSION* ) )
preferences:
212.09 ms | 402 KiB | 332 Q