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PHP: DOMXPath->evaluate() - Manual
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DOMXPath->__construct()DOMXPath->evaluate()
(No version information available, might be only in CVS)
DOMXPath->evaluate() — Evaluates the given XPath expression and returns a typed result if possible.
说明
DOMXPath
mixed evaluate ( string $expression [, DOMNode $contextnode ] )
Executes the given XPath expression and returns a typed result if possible.
参数
- expression
-
The XPath expression to execute.
- contextnode
-
The optional contextnode can be specified for doing relative XPath queries. By default, the queries are relative to the root element.
返回值
Returns a typed result if possible or a DOMNodeList containing all nodes matching the given XPath expression .
范例
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
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