(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.
The optional registerNodeNS can be specified to disable automatic registration of the context node.
Returns a typed result if possible or a DOMNodeList containing all nodes matching the given XPath expression.
If the expression is malformed or the contextnode is invalid, DOMXPath::evaluate() returns FALSE.
| 版本 | 说明 |
|---|---|
| 5.3.3 | The registerNodeNS parameter was added. |
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";
?>
以上例程会输出：
There are 2 english books