新手发个php修改XML的有关问题！

<br />$dom=new DOMDocument('1.0');<br />$dom->load('ceshi.xml');<br />$root=$dom->getElementsByTagName('online');<br />$root=$root->item(0);<br />$userid=$root->getElementsByTagName('userid');<br />foreach($userid as $b)<br />{<br />  foreach($b->attributes as $attr){ <br /><br />$value=$attr->nodeValue;<br />$name[].=$attr->nodeName;<br />{if($value=="xiao")<br />{  <br />   print_r($name);   <br /><br />}<br /><br /> }<br />}<br /><br />}<br />$dom->save('ceshi.xml');<br /><br />

<br /><br /><?xml version="1.0"?><br /><online> <br /><userid time="2007-06-13 11:20:08" ip="wangqile" label="wang">xiaxin</userid> <br /><userid time="2007-06-13 13:22:15" pp="dasdsa" label="xiao" ip="dasdsa">rwet</userid> <br /><userid time="2007-06-13 17:17:00" ip="dasdsa" label="ji"> gaoji</userid> <br /></online><br /><br /><br />