Cannot get attributes of nested SimpleXMLElement - php

Question

Clearly I'm missing something simple.
I have the following xml string which I parse using simplexml_load_string:
$xmlString = '<root><Title>Heading Text</Title><Image><img src="https://image.com?id=123" alt="alt text" /></Image></root>';
$xml = simplexml_load_string($xmlString);
However, I cannot access the img tag inside Image.
I would think I would use $xml->Image[0]->img to get the element and
$xml->Image[0]->img['src'] to get the url of the image. But I keep getting the error:
Trying to get property 'img' of non-object
$xml->Image[0] tests out as type SimpleXMLElement, and when I print_r() I get:
SimpleXMLElement Object (
[img] => SimpleXMLElement Object (
[#attributes] => Array (
[src] => https://image.com?id=123
[alt] => alt text
)
)
)
Like I said, I know I'm missing something really obvious, so any help would be appreciated.

Answer 1

You are correct, $xml->Image[0]->img['src'] will give you the src attribute, but it will give it to you as an object.
If you run print_r($xml->Image[0]->img['src']); it will show you this:
SimpleXMLElement Object
(
[0] => https://image.com?id=123
)
But if you run echo $xml->Image[0]->img['src']; instead, it will give you this:
https://image.com?id=123
The reason is that the SimpleXMLElement class implements the magic overload method __toString (or its equivalent in internal C code), so that whenever you cast the object to string, it will give you the string contents. Since echo always needs a string, it does this implicitly, but you can do it explicitly with (string), e.g.:
$imageSrc = (string)$xml->Image[0]->img['src'];
var_dump($imageSrc);
(As a side-note, the [0] is always optional - if you don't give a number, SimpleXML assumes you want the only or first child with that name, so $xml->Image->img['src'], $xml->Image[0]->img['src'], $xml->Image->img[0]['src'] and $xml->Image[0]->img[0]['src'] will all give the same result.)