3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = [1, 2, 3]; function foo(&$a) { $b = $a; $a[] = count($a) + 1; return $b; } var_dump( foo($a), // return value is *before* $a // after );
Output for 5.6.0 - 5.6.29, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) } array(4) { [0]=> int(1) [1]=> int(2) [2]=> int(3) [3]=> int(4) }
preferences:
138.68 ms | 408 KiB | 5 Q