3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array("one" => 1, "two" => 2); reset($a); $firstKey = key($a); echo $firstKey . "\n";
Output for 5.3.7 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.21, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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
one
preferences:
202.11 ms | 405 KiB | 268 Q