3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $a = null; var_dump(substr($a, -4, 4));
Output for 7.0.0 - 7.1.0
string(0) ""
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0
bool(false)