3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $original = array('hello'); $original[] = & $original; echo serialize($original);
Output for 5.1.0 - 7.1.7
a:2:{i:0;s:5:"hello";i:1;a:2:{i:0;s:5:"hello";i:1;R:3;}}
Output for 4.3.0 - 5.0.5
a:2:{i:0;s:5:"hello";i:1;a:2:{i:0;s:5:"hello";i:1;N;}}