3v4l.org

run code in 200+ php & hhvm versions
<?php $x = '#'; var_dump(substr( $x, 1 )); $x = ''; var_dump(substr( $x, 1 ));
based on Dk0Rg
Output for hhvm-3.15.4 - 3.22.0, 7.0.0 - 7.3.5
string(0) "" bool(false)
Output for 4.3.0 - 5.6.40, hhvm-3.10.1 - 3.13.2
bool(false) bool(false)