3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr1 = ["apple" => "bla", "peer" => "bleh"]; $arr2 = ["apple" => "foo", "bar" => "baz"]; $arr1Keys = array_keys($arr1); $arr2Keys = array_keys($arr2); $totalKeys = array_merge($arr1Keys, $arr2Keys); $totalKeys = $arr1Keys + $arr2Keys; var_dump($arr1Keys, $arr2Keys, $totalKeys);

preferences:
53.18 ms | 406 KiB | 5 Q