3v4l.org

run code in 300+ PHP versions simultaneously
<?php function sum($arr) { if ( empty($arr) ) { return; } return $arr[0] + sum(array_slice($arr, 1)); } function rev($str) { if ( ! $str ) { return; } return rev(substr($str,1)) . $str{0}; } echo sum(array(1,2,3,4,5)); echo rev('hola mundo');

preferences:
36.59 ms | 402 KiB | 5 Q