XmlDocument 转换为xml字符串

static public string XMLDocumentToString(XmlDocument doc)

    {

        MemoryStream stream = new MemoryStream();

        XmlTextWriter writer = new XmlTextWriter(stream, null);

        writer.Formatting = Formatting.Indented;

        doc.Save(writer);

StreamReader sr = new StreamReader(stream, System.Text.Encoding.UTF8);

        stream.Position = 0;

        string xmlString = sr.ReadToEnd();

        sr.Close();

        stream.Close();

return xmlString.Replace("<?xml version=\"1.0\"?>","");

    }