Online PHP editor | output for T8oOS

<?php $arr = [ 'children' => [ 'a.class-1.php' => [], 'a' => [], 'a-1.class-1' => [], 'a.class.php' => [], 'a.class' => [], 'a-1.class-1.php-1' => [], 'a-1.class.php' => [], 'a-1' => [], 'a.class-1.php-1' => [], 'a.class.php-1' => [], ] ]; uksort($arr['children'], function($a, $b){ $a = explode('.', $a); $b = explode('.', $b); $s = ''; $i = 0; while (isset($a[$i]) && isset($b[$i]) && $a[$i] == $b[$i]) { $s .= $a[$i++] . '.'; } return $s . ($a[$i] ?? '') <=> $s . ($b[$i] ?? ''); }); print_r(array_keys($arr['children']));