在PHP上使用xpath：如何选择第一个孩子？

I have an XML structure like this one:

<layout>
    <pattern> ... </pattern>
    <row> ... </row>
</layout>

How can I select the first node of <layout> by its index, using XPath?

w3schools indicates syntax similar to /bookstore/book[1]/title, but then says:

There is a problem with this. The example above shows different results in IE and other browsers.

IE5 and later has implemented that [0] should be the first node, but according to the W3C standard it should have been [1]!!

A Workaround!
To solve the [0] and [1] problem in IE5+, you can set the SelectionLanguage to XPath.

But that's client-specific. The PHP manual isn't very clear about this either.

As Felix said: What about trying?

$l = new SimpleXMLElement('<layout>
  <pattern> ... </pattern> 
  <row> ... </row>  
</layout>');
foreach($l->xpath('/layout/*[1]') as $n) {// yeah yeah, it's only one....
  echo $n->getName();
}

prints pattern. (php 5.3.1/win32/php.net build)