DOMDocument:saveXML返回值替空字符串

DOMDocument::saveXML 返回值为空字符串
PHP手册中的的实例：

        $doc = new DOMDocument('1.0');

	// we want a nice output

	$doc->formatOutput = true;



	$root = $doc->createElement('book');

	$root = $doc->appendChild($root);



	$title = $doc->createElement('title');

	$title = $root->appendChild($title);



	$text = $doc->createTextNode('This is the title');

	$text = $title->appendChild($text);



		

	echo "Saving all the document:\n";

	

	$xmlContent = $doc->saveXML();

	

	var_dump($xmlContent);

打印出的结果是：
Saving all the document: string(72) " "

为什么没有打印出完整的XML？请各位前辈指点，Thanks! PHP saveXML

分享到：

------解决方案--------------------
请在文本方式下查看

Saving all the document:

string(72) "



  



"