- var_dump: documentation ( source)
- array_filter: documentation ( source)
<?php
$values = array('1','2');
$is_multidim = (bool) count(array_filter($values, 'is_array'));
var_dump($is_multidim);
var_dump(isset($values[0]), $values[0]);
var_dump(isset($values[0][0]), $values[0][0]);