3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $s = 'abcdefghijklm'; for($i=strlen($s)-1, $j=0; $j<$i; $i--, $j++) { list($s[$j], $s[$i]) = array($s[$i], $s[$j]); } echo $s;
based on IIptj
Output for 4.3.0 - 7.2.0
mlkjihgfedcba