3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr=array(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8); $arr = array_reduce($arr, function($a, $b) { return $a ^ $b; }); echo $arr[0];

preferences:
56.66 ms | 402 KiB | 5 Q