3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $a = 1; $$a = 1; ${$a++} = 2; var_dump(${1}); var_dump($a); var_dump(${2});
Output for 5.5.0 - 7.1.0
int(2) int(2) Notice: Undefined variable: 2 in /in/16qPd on line 7 NULL
Output for 4.3.0 - 5.4.45
int(2) int(2) NULL