3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a1 = [ "a" => 2, "b" => 0, "c" => 5, ]; $a2 = [ "a" => 3, "b" => 9, "c" => 7, "d" => 10, ]; $result = $a1; foreach ($a2 as $k => $v) { $result[$k] = ($result[$k] ?? 0) + $v; } var_export($result);

preferences:
55.54 ms | 1003 KiB | 5 Q