- var_dump: documentation ( source)
- date_create: documentation ( source)
- time: documentation ( source)
<?php
$a = array(15 => null, 16 => true);
var_dump(array_key_exists(15, $a));
var_dump(isset($a[15]));
var_dump(array_key_exists(16, $a));
var_dump(date_create(time()));