public static string XmlDocumentAsString(XmlDocument doc, Encoding enc)
{
    using (MemoryStream ms = new MemoryStream())
    {
            XmlTextWriter xtw = new XmlTextWriter(ms, enc);
        xtw.Formatting = Formatting.Indented;
        doc.Save(xtw);
        return enc.GetString(ms.ToArray());
    }
}