php简单的xml子节点号加

Question

I want use php simple xml parse some tree like this.

how to plus all the tree->item->object->num?

I want get an int 16 (2 + 4 + 7 + 2 + 1)

<tree>
  <item>
    <object>
      <num>2</num>
    </object>
    <object>
      <num>4</num>
    </object>
  </item>
  <item>
    <object>
      <num>7</num>
    </object>
    <object>
      <num>2</num>
    </object>
  </item>
  <item>
    <object>
      <num>1</num>
    </object>
  </item>
</tree>

Answer 1

Simple/ugly version:

$dom = new DOMDocument();
$dom->loadXML($your_xml);

$xp = new DOMXPath($dom);

$nums = $xp->query('//num');
$sum = 0;
foreach($nums as $num) {
   $sum += $num->nodeValue;
}
echo $sum;