Online PHP editor | output for BthA0

<?php $arr = array ( 0 => 'FOLDER./Images.Vacation.2018', 1 => './Images.Vacation.2018/Racoon001.jpg', 2 => './Images.Vacation.2018/Racoon002.txt', 3 => './Images.Vacation.2018/the.racoon.swimming.mp4', 4 => './Images.Vacation.2018/the.racoon.swimming.slv', 5 => 'FOLDER./WestImages', 6 => './WestImages/Ramco.txt', 7 => './WestImages/Ramco.jpg', 8 => 'FOLDER./WestImages/Subimages', 9 => './WestImages/Subimages/Image001.jpg', 10 => './WestImages/Subimages/Image002.jpg', 11 => './WestImages/West.Ramco.Swimming.mp4', ); $folders = preg_grep("/^FOLDER.*/", $arr); foreach($folders as $folder){ $result[] = $folder; $result = array_merge($result, preg_grep("/^\." . str_replace(["FOLDER.", "/"], ["","\/"], $folder) . "\/[A-Za-z0-9\.]+$/", $arr)); } var_dump($result);