PHP registerXPathNamespace() 函数

<?php  
$xml=<<<XML
<book xmlns:chap="http://example.org/chapter-title">  
<title>My Book</title>  
<chapter id="1">  
<chap:title>Chapter 1</chap:title>  
<para>Donec velit. Nullam eget tellus...</para>  
</chapter>  
<chapter id="2">  
<chap:title>Chapter 2</chap:title>  
<para>Lorem ipsum dolor sit amet....</para>  
</chapter>  
</book>  
XML;  

$sxe=new SimpleXMLElement($xml);  
$sxe->registerXPathNamespace('c','http://example.org/chapter-title');  
$result=$sxe->xpath('//c:title');  
foreach ($result as $title)  
{  
echo $title . "<br>";  
}  
?>

registerXPathNamespace( _prefix_ , _ns_ );