(PHP 5 >= 5.1.0)
DOMXPath::evaluate — Evaluates the given XPath expression and returns a typed result if possible.
Executes the given XPath expression and returns a typed result if possible.
The XPath expression to execute.
The optional contextnode can be specified for doing relative XPath queries. By default, the queries are relative to the root element.
Returns a typed result if possible or a DOMNodeList containing all nodes matching the given XPath expression .
Example #1 Getting the count of all the english books
<?php
$doc = new DOMDocument;
$doc->load('book.xml');
$xpath = new DOMXPath($doc);
$tbody = $doc->getElementsByTagName('tbody')->item(0);
// our query is relative to the tbody node
$query = 'count(row/entry[. = "en"])';
$entries = $xpath->evaluate($query, $tbody);
echo "There are $entries english books\n";
?>
上例将输出：
There are 2 english books