3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = "hello"; $b = "hi"; $val = "a"; echo $$val; // outputs "hello" echo "\n"; $val = "b"; echo $$val; // outputs "hi"
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.32, 8.0.0 - 8.0.24, 8.1.0 - 8.1.11
hello hi

preferences:
64.5 ms | 411 KiB | 5 Q