3v4l.org

run code in 300+ PHP versions simultaneously
<?php $x = [ 'foo' => [], 'biz' => [ 'baz' => [] ] ]; var_dump(array_filter($x));
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 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(1) { ["biz"]=> array(1) { ["baz"]=> array(0) { } } }
preferences:
174.78 ms | 404 KiB | 228 Q