3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $a= null; $b = 20; echo '<br>a-'. $a; $c = $b + $a; echo '<br>c-'.$c; $a = $a + $b; echo '<br>na-'.$a;
Output for 4.3.0 - 5.6.28, hhvm-3.12.0, 7.0.0 - 7.1.0
<br>a-<br>c-20<br>na-20
Output for hhvm-3.10.0

Process exited with code 153.