- var_dump: documentation ( source)
- implode: documentation ( source)
<?php
$arr1 = array('req'=>false, 'lessthan'=>10);
$arr2 = array('parent'=> array('parent_name'=>array('val1'), 'rules'=>array('req'=>false)));
$arr3 = array('a', 'b', 'c');
$arrE = array();
$arrE = implode(',', $arr3);
var_dump($arrE);