3v4l.org

run code in 500+ PHP versions simultaneously
<?php $keys = ["first", "second", "third"]; $array = []; foreach(array_reverse($keys) as $key) { $temp = $array; unset($array[key($array)]); $array[$key] = $temp; } $array['first']['second']['third'] = 'value'; print_r($array);
Output for 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Array ( [first] => Array ( [second] => Array ( [third] => value ) ) )

preferences:
103.91 ms | 1390 KiB | 4 Q