PHP DOMnode。 如何检查是否配对？

I have some tags in XML document:

      <kat1>42</kat1>
      <kat2/>
      <kat3/>

and if DOMNode $myNode is "kat2"

$myNode->nodeValue

returns zero instead of null. How to check if it is not paired tag and return NULL if true, else value.

Demo

<tag /> is the exact same thing as <tag></tag> so, all you have to do is check whether or not it's empty. If it's empty it wil be printed as a single tag, if it's not empty it will be be printed with both opening and closing tags.