3v4l.org

run code in 300+ PHP versions simultaneously
<?php $strings = ["folders/folder1/folder5/../../folder2", "folders/folder1/../../../folder2", "folders/folder1/folder5/../folder2"]; foreach ($strings as $url) { echo preg_replace('~(?<=/|^)(?!\.\.(?![^/]))[^/\n]+/(?R)?\.\.(?:/|$)~', '', $url) . PHP_EOL; }

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24.8 ms | 404 KiB | 5 Q