3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php function square($x) { return $x * $x; } echo square(42);
based on W1CKN
Output for 4.3.0 - 7.1.7, 7.2.0
1764
Output for 7.1.10

Process exited with code 137.