3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php function ackermann( $m , $n ) { if ( $m==0 ) { return $n + 1; } elseif ( $n==0 ) { return ackermann( $m-1 , 1 ); } return ackermann( $m-1, ackermann( $m , $n-1 ) ); } echo ackermann( 4, 0 ); ?>
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
13