As per the documentation, you need to specify true as the second argument if you want an associative array instead of an object from json_decode. This would be the code:

$result = json_decode($jsondata, true);

If you want integer keys instead of whatever the property names are:

$result = array_values(json_decode($jsondata, true));

However, with your current decode you just access it as an object:

print_r($obj->Result);

$string = file_get_contents('./string.json');
$json = json_decode($string);

if you want to have items: <address>:

foreach ($json['items'] as $address)
{
    echo "items:". $address['address'] ."\n";
};

anyway if you are not sure about how an array is built you could print it via:

print_r($json);

which will print:

Array
(
    [items] => Array
        (
            [0] => Array
                (
                    [address] => W 7th Ave
                )

            [1] => Array
                (
                    [address] => W 8th St
                )
        )
)

now you found out that $json contains just an array (items) of two array, then, if you loop it, you will get that array which is printed in your example. As explained above you need to go one step deeper by looping the elements in your items array and print their address element.

here is the complete script: http://pastie.org/2275879