Sorting Prices from XML

Answer 1

1.Get them from XML (you seem to be able to do that).
2.Put them in an array
3.sort() the array, if your items are more complex. possibly using usort():

$d =  new SimpleXMLElement('<root>
  <item>
    <price>1234</price>
  </item>
  <item>
    <price>4123</price>
  </item>
  <item>
    <price>3142</price>
  </item>
  <item>
    <price>2431</price>
  </item>
</root>');
$items = array();
foreach($d->item as $item) $items[] = $item;
function _mysort($a,$b){return $a->price - $b->price;}
usort($items,'_mysort');
var_dump($items);

Answer 2

I recently disocvered SimpleDOM for a project where I needed a more advanced xpath system. I really like it and I think it could do what you're looking for. You can find it (docs are bundled in the source code download) here: http://code.google.com/p/simpledom/

You'll want to look at the sortedXPath() method I believe:

sortedXPath (line 888)

Run an XPath query and sort the result

This method accepts any number of arguments in a way similar to array_multisort()

   1. // Retrieve all <x/> nodes, sorted by @foo ascending, @bar descending
   2. $root->sortedXPath('//x', '@foo', '@bar', SORT_DESC);
   3. 
   4. // Same, but sort @foo numerically and @bar as strings
   5. $root->sortedXPath('//x', '@foo', SORT_NUMERIC, '@bar', SORT_STRING, SORT_DESC);

    * access: public

void sortedXPath (string $xpath)

    * string $xpath: XPath expression