3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = array('foo' => null); var_export($array); echo "\nisset? "; var_export(isset($array['foo'])); echo "\narray_key_exists? "; var_export(array_key_exists('foo', $array)); echo "\n";
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 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
array ( 'foo' => NULL, ) isset? false array_key_exists? true
preferences:
268.77 ms | 406 KiB | 330 Q