不要在XML上使用正则表达式。Xml不是常规语言。请改用php的xml扩展名：
$xml = new SimpleXml(file_get_contents($xmlFile));function process_recursive($xmlNode) { $xmlNode->addAttribute('attr', 'myAttr'); foreach ($xmlNode->children() as $childNode) { process_recursive($childNode); }}process_recursive($xml);echo $xml->asXML();所有包含正则表达式的答案都将破坏此有效xml，例如：
<?xml version="1.0" encoding='UTF-8'?><html> <head> <!-- <meta> ... </meta> --> <script>//<![CDATA[ function load() {document.write('<tt>Test</tt>');} //]]></script> <title><![CDATA[Fancy <<SiteName>> [with Breadcrumbs] > in > title]]></title> </head> <body onload="load()"> <input type="submit" value="multiline button text" /> </body></html>
