3v4l.org

run code in 300+ PHP versions simultaneously
<?php $one = array(2 => '2'); $two = array(2 => '2'); $three = array(3 => '3'); print_r(array_merge($one, $two)); print_r($one + $two + $three); $two += $one; print_r($two);

preferences:
52.19 ms | 402 KiB | 5 Q