主从结构的JSON要怎么分拆

array (  'head' =>   array (    'id' => '4',    'userno' => '12345',    'username' => 'CDZ1',  ),  'body' =>   array (    0 =>     array (      'orderno' => '1',      'price' => '15.00',      'qty' => '1',    ),    1 =>     array (      'orderno' => '1',      'price' => '9.00',      'qty' => '1',    ),  ),)

<?php @header("Content-type: text/html; charset=utf-8");$a='{"head":{"id":"4","userno":"12345","username":"CDZ1"},"body":[{"orderno":"1","price":"15.00","qty":"1"},{"orderno":"1","price":"9.00","qty":"1"}]}';$obj=json_decode($a);echo 'userno:'.$obj->head->userno;echo '<br/>price:'.$obj->body[0]->price;/////或：echo "<br/><br/><br/>";$ary=json_decode($a,true);echo 'userno:'.$ary['head']['userno'];echo '<br/>price:'.$ary['body'][0]['price'];?>