3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = [1 => "As", 3 => "asdf"]; $aras = array_fill_keys([2,4,5], array()); $asrr = [2 => [], 3 => "ASdasfas"]; print_r($arr + $aras); print_r($aras);

preferences:
59.25 ms | 402 KiB | 5 Q