DOMXPath->evaluate()
(no version information, might be only in CVS)
DOMXPath->evaluate() --
Evaluates the given XPath expression and returns a typed result if possible.
说明
class
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
例子 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
|
|