3v4l.org

run code in 500+ PHP versions simultaneously
<?php $test = []; $test['1'] = 'integer'; var_dump($test); var_dump(array_keys($test));
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.31, 8.4.1 - 8.4.22, 8.5.0 - 8.5.7
array(1) { [1]=> string(7) "integer" } array(1) { [0]=> int(1) }
preferences:
96.88 ms | 1272 KiB | 4 Q