3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php echo date("W", mktime(0, 0, 0, 12, 31, 2012)); ?>
Output for 4.4.1 - 4.4.9, 5.0.5 - 7.2.0
01
Output for 4.3.0 - 4.4.0, 5.0.0 - 5.0.4
1