3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = ['1' => 'value']; $keys = array_keys($a); var_dump($a); var_dump($keys);
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.7, 7.2.29 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.31, 8.2.0 - 8.2.27, 8.3.0 - 8.3.15, 8.4.1 - 8.4.2
array(1) { [1]=> string(5) "value" } array(1) { [0]=> int(1) }
preferences:
43.63 ms | 407 KiB | 5 Q