$contents = "<?xml version='1.0' ?>
<authed>1</authed>
<book>read</book>";
我有一个像这样的xml字符串我想在根标签内添加所有元素
像这样
$contents = "<?xml version='1.0' ?>
<root>
<authed>1</authed>
<book>read</book>
</root>";