3v4l.org

run code in 300+ PHP versions simultaneously
<?php //$s = ''; print "isset: '" . isset($s) . "'. "; //print "!empty: '" . !empty($s) . "'"; ?>
Output for 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.7, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
isset: ''.
preferences:
156.72 ms | 404 KiB | 190 Q