PHP对象运算符是数字

Question

My code gets some data from an API which comes back like:

stdClass Object
(
    [http_response_body] => stdClass Object
        (
            [items] => Array
                (
                    [0] => stdClass Object
                        (
                            [tags] => Array
                                (
                                )

I am trying to display the data such as [tags] and I am using

print_r($d->http_response_body->items);

Which works fine, until I want to get the array item called [0]. The code doesnt like:

print_r($d->http_response_body->items->0);

How can I get to accept the 0 after the items-> bit. I've tried all sorts of stuff such as '0' {'0'} [0] and nothing works.

Thanks