请教一个php删除xml节点的问题,看代码

Question

<?php
error_reporting(7);
header("Content-type:text/xml");
$str = '<?xml version="1.0" encoding="utf-8"?>
<Data id="yuanyongzhi">
  <RoomRateDetail id="9">
    <CityCode/>
    <PropertyID>1E5AV</PropertyID>
    <CheckInDate>20090410</CheckInDate>
    <CheckOutDate>20090430</CheckOutDate>
    <Rank>4A</Rank>
    <HotelEnglishName>YinHai BaiLing Hotel</HotelEnglishName>
    <PassengerType>A</PassengerType>
  </RoomRateDetail>
<RoomRateDetail id="8">
    <CityCode/>
    <PropertyID>1E5AV</PropertyID>
    <CheckInDate>20090410</CheckInDate>
    <CheckOutDate>20090430</CheckOutDate>
    <Rank>4A</Rank>
    <HotelEnglishName>YinHai BaiLing Hotel</HotelEnglishName>
    <PassengerType>A</PassengerType>
  </RoomRateDetail><RoomRateDetail id="12">
    <CityCode/>
    <PropertyID>1E5AV</PropertyID>
    <CheckInDate>20090410</CheckInDate>
    <CheckOutDate>20090430</CheckOutDate>
    <Rank>4A</Rank>
    <HotelEnglishName>YinHai BaiLing Hotel</HotelEnglishName>
    <PassengerType>A</PassengerType>
  </RoomRateDetail><RoomRateDetail id="0">
    <CityCode/>
    <PropertyID>1E5AV</PropertyID>
    <CheckInDate>20090410</CheckInDate>
    <CheckOutDate>20090430</CheckOutDate>
    <Rank>4A</Rank>
    <HotelEnglishName>YinHai BaiLing Hotel</HotelEnglishName>
    <PassengerType>A</PassengerType>
</RoomRateDetail>
</Data>';$id = (int)$_GET['id']; //选择你要删除的节点ID
$doc = new DOMDocument;
$doc->loadXML($str);
$book = $doc->documentElement;
$items = $book->getElementsByTagName('RoomRateDetail');for($i = 0; $i < $items->length; $i++)
{
if((int)$items->item($i)->getAttribute("id") == $id)
{
$book->removeChild($items->item($i));
break;
}
}
echo $doc->saveXML();
?>