string get_attribute(DOMElement* element, string name)
{
   XMLCh* xname = new XMLCh[name.length() + 1];
   XMLString::transcode(name.c_str(),
      xname, name.length());
   XMLCh* xvalue = element->getAttribute(xname);
   delete xname;
   return XMLCh_to_string(xvalue);
}

string attribute_value = get_attribute(
   price_element, "currency");