run code in 200+ php & hhvm versions
Bugs & Features
<?php $str = "abcdefghijklmn"; $print = strrev($str); $st=""; for($i = 0;$i<$print.length;$i=$i+2) { if($i < $print.length - ) $st .= substr($print,$i,$i+1); echo $st; }

Here you find the average performance (time & memory) of each version. A grayed out version indicates it didn't complete successfully (based on exit-code).
Note: hhvm uses a JIT which only kicks in after a few runs. Since we run scripts only once, hhvm always runs slower.

VersionSystem time (s)User time (s)Memory (MiB)