3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = ['foo', 'bar']; foreach(array_keys($arr) as $key) { var_dump($key); } $arr = ['foo' => 'foo', 'bar' => 'bar']; foreach(array_keys($arr) as $key) { var_dump($key); }
Output for 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
int(0) int(1) string(3) "foo" string(3) "bar"

preferences:
48.89 ms | 406 KiB | 5 Q