domxpath.evaluate.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Evaluates the given XPath expression and returns a typed result if possible.</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="domxpath.construct.html">DOMXPath::__construct</a></div> <div class="next" style="text-align: right; float: right;"><a href="domxpath.query.html">DOMXPath::query</a></div> <div class="up"><a href="class.domxpath.html">DOMXPath</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="domxpath.evaluate" class="refentry"> <div class="refnamediv"> <h1 class="refname">DOMXPath::evaluate</h1> <p class="verinfo">(No version information available, might be only in CVS)</p><p class="refpurpose"><span class="refname">DOMXPath::evaluate</span> — <span class="dc-title"> Evaluates the given XPath expression and returns a typed result if possible. </span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <span class="methodname"><b><b>DOMXPath::evaluate</b></b></span> ( <span class="methodparam"><span class="type">string</span> <tt class="parameter">$expression</tt></span> [, <span class="methodparam"><span class="type"><a href="class.domnode.html" class="type DOMNode">DOMNode</a></span> <tt class="parameter">$contextnode</tt></span> ] )</div> <p class="para rdfs-comment"> Executes the given XPath <i><tt class="parameter">expression</tt></i> and returns a typed result if possible. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">expression</tt></i></span> <dd> <p class="para"> The XPath expression to execute. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">contextnode</tt></i></span> <dd> <p class="para"> The optional <i><tt class="parameter">contextnode</tt></i> can be specified for doing relative XPath queries. By default, the queries are relative to the root element. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns a typed result if possible or a <a href="class.domnodelist.html" class="classname">DOMNodeList</a> containing all nodes matching the given XPath <i><tt class="parameter">expression</tt></i>. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Getting the count of all the english books</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br />$doc </span><span style="color: #007700">= new </span><span style="color: #0000BB">DOMDocument</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$doc</span><span style="color: #007700">-></span><span style="color: #0000BB">load</span><span style="color: #007700">(</span><span style="color: #DD0000">'book.xml'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$xpath </span><span style="color: #007700">= new </span><span style="color: #0000BB">DOMXPath</span><span style="color: #007700">(</span><span style="color: #0000BB">$doc</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$tbody </span><span style="color: #007700">= </span><span style="color: #0000BB">$doc</span><span style="color: #007700">-></span><span style="color: #0000BB">getElementsByTagName</span><span style="color: #007700">(</span><span style="color: #DD0000">'tbody'</span><span style="color: #007700">)-></span><span style="color: #0000BB">item</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// our query is relative to the tbody node<br /></span><span style="color: #0000BB">$query </span><span style="color: #007700">= </span><span style="color: #DD0000">'count(row/entry[. = "en"])'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$entries </span><span style="color: #007700">= </span><span style="color: #0000BB">$xpath</span><span style="color: #007700">-></span><span style="color: #0000BB">evaluate</span><span style="color: #007700">(</span><span style="color: #0000BB">$query</span><span style="color: #007700">, </span><span style="color: #0000BB">$tbody</span><span style="color: #007700">);<br />echo </span><span style="color: #DD0000">"There are $entries english books\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents"><pre><div class="cdata"><pre>There are 2 english books</pre></div> </pre></div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="domxpath.query.html" class="xref">DOMXPath::query</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="domxpath.construct.html">DOMXPath::__construct</a></div> <div class="next" style="text-align: right; float: right;"><a href="domxpath.query.html">DOMXPath::query</a></div> <div class="up"><a href="class.domxpath.html">DOMXPath</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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