To Read, Write, append and Edit To XML File

Write To The XML File:
filename = Server.MapPath("test.xml");
string strId = "1";
string strFourmName = "NewlyDiagnose";
string strTopic = "how r u";
string strUserName = "jaimin";
string strPostBy = "modi";
string strDate = "11/11/2007";

XmlTextWriter xtw = new XmlTextWriter(filename, null);
xtw.Formatting = Formatting.Indented;
xtw.WriteStartDocument();
xtw.WriteStartElement(strFourmName);
xtw.WriteStartElement("item");
xtw.WriteAttributeString("Id", strId);
xtw.WriteElementString("Topic", strTopic);
xtw.WriteElementString("UserName", strUserName);
xtw.WriteElementString("PostBy", strPostBy);
xtw.WriteElementString("Date", strDate);
xtw.WriteEndElement();
xtw.WriteEndElement();
xtw.WriteEndDocument();
xtw.Flush();
xtw.Close();

// for append file.........
XmlDocument doc = new XmlDocument();
doc.Load(Server.MapPath("test.xml"));
XmlElement s = doc.CreateElement("item");
s.SetAttribute("Id", "2");
XmlElement Topic = doc.CreateElement("Topic");
Topic.InnerText = "Hi";
XmlElement UserName = doc.CreateElement("UserName");
UserName.InnerText = "Himanshu";
XmlElement PostBy = doc.CreateElement("PostBy");
PostBy.InnerText = "Me";
XmlElement Date = doc.CreateElement("Date");
Date.InnerText = strDate;
s.IsEmpty = false;
s.AppendChild(Topic);
s.AppendChild(UserName);
s.AppendChild(PostBy);
s.AppendChild(Date);
doc.DocumentElement.AppendChild(s);
//doc.DocumentElement.AppendChild(Topic);
//doc.DocumentElement.AppendChild(UserName);
//doc.DocumentElement.AppendChild(PostBy);
//doc.DocumentElement.AppendChild(Date);
doc.Save(Server.MapPath("test.xml"));

//For edit in file....
XmlDocument xmldocedit = new XmlDocument();
xmldocedit.Load(Server.MapPath("test.xml"));
XmlNode xmlnode = xmldocedit.SelectSingleNode("/NewlyDiagnose/item[@id='2']");
xmlnode.ChildNodes[0].InnerText = "Hello Changed Himanshu";
xmldocedit.Save(Server.MapPath("test.xml"));

//For Delete the node
XmlDocument xmldocdelete = new XmlDocument();
xmldocdelete.Load(Server.MapPath("test.xml"));
XmlNode xmlnodeDelete = xmldocdelete.SelectSingleNode("/NewlyDiagnose/item[@id='2']");
xmlnodeDelete.ChildNodes[0].RemoveAll();
xmldocdelete.Save(Server.MapPath("test.xml"));

//To Read XML File
filename = Server.MapPath("test.xml");
string strVale = "";
XmlTextReader xtr = new XmlTextReader(filename);
while (xtr.Read())
{
if (xtr.NodeType == XmlNodeType.Text)
{
strVale += xtr.Value+",";
}
if (xtr.NodeType == XmlNodeType.EndElement)
{
if (xtr.LocalName == "item")
{
strVale = strVale.Substring(0, strVale.Length - 1);
strVale += "*";
}
}
}
strVale = strVale.Substring(0, strVale.Length - 1);
strAry = strVale.Split('*');