3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $card_no = "0012345678901"; $no = str_pad(substr($card_no, -4), strlen($card_no), 'X', STR_PAD_LEFT); echo $no; ?>
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
XXXXXXXXX8901