Reading is easy (this example, I should probably close the file.... oops)
Qt Code: 
  1. QString filename = "C:/test.xml";
  2.     QFile file(filename);
  3.     if (!file.open(QFile::ReadOnly | QFile::Text))
  4.     {
  5.         qDebug(qPrintable(QString("Error: Cannot read file %1 %2").arg(filename).arg(file.errorString())));
  6.         return;
  7.     }
  9.     doc.setContent(&file);
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Is your real concern related to processing? Consider this small example that traverses a DOM tree
Qt Code: 
  1. void pp(QTextStream& os, QDomNode node)
  2. {
  3.     while (!node.isNull())
  4.     {
  5.         if (node.isElement())
  6.         {
  7.             // Ignore attributes for now.
  8.             //qDebug(qPrintable(QString("DEBUG: <%1>").arg(node.toElement().tagName())));
  9.             os << "<" << node.toElement().tagName() << ">";
  10.             if (node.hasChildNodes())
  11.             {
  12.                 QDomNode childNode = node.firstChild();
  13.                 pp(os, childNode);
  14.             }
  15.             // Print all children
  16.             //qDebug(qPrintable(QString("DEBUG: </%1>").arg(node.toElement().tagName())));
  17.             os << "</" << node.toElement().tagName() << ">";
  18.         }
  19.         else if (node.isText())
  20.         {
  21.             os << node.toText().data();
  22.         }
  23.         else
  24.         {
  25.             qDebug(qPrintable(QString("Unexpected node type:")));
  26.             //qDebug(qPrintable(QString("Unexpected node type: %1").arg((int)(node.NodeType()))));
  27.         }
  28.         node = node.nextSibling();
  29.     }
  30. }
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The example ignores attributes. The head node that I would pass as an argument is found using doc.documentElement().
This snippet copies a node out of a DOM tree and removes the node. I then insert the node in a different location.
Qt Code: 
  1. QString xmlOriginal = "<xml><item><a>1</a></item><item><a>2</a></item></xml>";
  3.     doc.setContent(xmlOriginal);
  4.     QDomElement docElement = doc.documentElement();
  5.     QDomNode firstChild = docElement.firstChild();
  6.     QDomNode secondChild = firstChild.nextSibling();
  7.     QDomNode clonedNode = secondChild.cloneNode(true);
  8.     doc.documentElement().removeChild(secondChild);
  9.     doc.documentElement().insertBefore(clonedNode, firstChild);
  10.     QString s2;
  11.     QTextStream os2(&s2);
  12.     os2 << "\nStream *****\n" << doc;
  13.     qDebug(qPrintable(s2));
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