3v4l.org

run code in 200+ php & hhvm versions
<?php $s = ''; print "isset: '" . isset($s) . "'. "; print "!empty: '" . !empty($s) . "'"; ?>
based on iTeoX
Output for 4.3.0 - 5.6.40, hhvm-3.10.1 - 3.22.0, 7.0.0 - 7.4.0alpha2
isset: '1'. !empty: ''