3v4l.org

run code in 500+ PHP versions simultaneously
<?php $name = array("page18.jpg","page16.jpg","page17.jpg","page19.jpg",); foreach($name as $val) { $new_name[] = preg_replace('/\D/', '', $val); } print_r($new_name);

preferences:
108.25 ms | 2665 KiB | 5 Q