- var_dump: documentation ( source)
<?php
$test = array();
$test['parent'] = array();
$test['parent']['child'] = 'foo';
$test['parent'][false] = 'bar';
$test['parent'][null] = 'baz';
var_dump($test);
var_dump($test['parent'][(string) null]);
var_dump($test['parent'][(string) false]);