3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php var_dump(key(array()));
Output for 4.4.1, 5.1.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
NULL
Output for 4.3.2 - 4.4.0, 4.4.2 - 5.0.5
Fatal error: Only variables can be passed by reference in /in/1ugoX on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1
Fatal error: Only variables can be passed by reference in /in/1ugoX on line 3