3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $a = array(); $arrayKey = '[0][1]'; $a[0][1] = "two levels deep"; echo $a[$arrayKey];
based on 7RXAJ
Output for 5.3.0 - 7.2.0
Notice: Undefined index: [0][1] in /in/90TtN on line 8
Output for 4.3.0 - 5.2.17
Notice: Undefined index: [0][1] in /in/90TtN on line 8