PHP registerXPathNamespace() 函数

为下一个 XPath 查询创建命名空间上下文：

   <?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>";
   }
  ?>