3v4l.org

run code in 300+ PHP versions simultaneously
<?php $foo = 2; $baa = ($foo*2); $x = [$foo => $baa]; print_r($x);
Output for 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 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Array ( [2] => 4 )

preferences:
206.16 ms | 404 KiB | 326 Q