3v4l.org

run code in 300+ PHP versions simultaneously
<?php class Haha { const HEH='wow'; } $nest='HEH'; $nest2='nest'; echo constant('Haha::'.$$nest2);
Output for 5.6.38, 7.1.0 - 7.1.22, 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 - 8.1.29, 8.2.0 - 8.2.20, 8.3.0 - 8.3.8
wow

preferences:
156.71 ms | 404 KiB | 176 Q