Online PHP editor | refs for E9i6C

<?php $pages = [ 'a' => ['title' => 'A'], 'c' => ['title' => 'C'], 'b' => ['title' => 'B'], 'n' => ['title' => '.N'], ]; $keys = []; foreach ($pages as $p) { if (! isset($keys[$p['title']])) { $keys[$p['title']] = preg_replace('_^[^0-9a-z]*_', '', strtolower($p['title'])); } } uasort($pages, fn($a, $b) => $keys[$a['title']] <=> $keys[$b['title']]); echo implode(', ', array_map(fn($page) => $page['title'], $pages));