3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $string = "foo"; $a = "string"; $b = $$a[0]; var_dump($b);
Output for 7.0.0 - 7.1.0
string(1) "f"
Output for 5.0.4 - 5.6.28, hhvm-3.10.0 - 3.12.0
Notice: Undefined variable: s in /in/jHunM on line 6 NULL
Output for 4.3.0 - 5.0.3
Notice: Undefined variable: s in /in/jHunM on line 6 NULL