3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php ${0x0} = 'test'; $var = "0"; echo $$var;
Output for 4.3.0 - 5.6.28, 7.0.0 - 7.1.0
test
Output for hhvm-3.10.0 - 3.13.2
Notice: Undefined variable: 0 in /in/6AF4l on line 5