3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php function f($n) { if ($n < 2) return $n; return $n * f(--$n); } echo f(20);
Output for 5.1.0 - 7.1.0
121645100408832000
Output for 4.3.0 - 5.0.5
2432902008176640000