3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a='d'; $b='a'; $c='b'; $d='a'; echo "$a {$$a} $$$a $$$a $$$$a $$$$$a";
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0, 7.1.6 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
d a $$d $$d $$$d $$$$d
Output for 7.1.5

Process exited with code 137.
preferences:
265.82 ms | 401 KiB | 399 Q