Asp. NET read-write XML File Sample code

The public void Setxmlfilevalue (string xmlpath,string appkey,string appvalue)/write Xmlpath is the file path + filename, Appkey is Key name, Appvalue is value
{
XmlDocument xdoc = new XmlDocument ();
Xdoc.load (Xmlpath);
XmlNode XNode;
XmlElement xElem1;
XmlElement xElem2;

XNode = Xdoc.selectsinglenode ("//appsettings");

XElem1 = (XmlElement) xnode.selectsinglenode ("//add[@key = '" + Appkey + "']");
if (xElem1!= null)
{
Xelem1.setattribute ("value", appvalue);
}
Else
{
XELEM2 = Xdoc.createelement ("add");
Xelem2.setattribute ("Key", Appkey);
Xelem2.setattribute ("value", appvalue);
Xnode.appendchild (XELEM2);
}
Xdoc.save (Xmlpath);
}

The public void Getxmlfilevalue (string xmlpath,string appkey,ref string appvalue)/Read Xmlpath is the file path + filename, Appkey is the Key name, Appvalue is value
{
XmlDocument xdoc = new XmlDocument ();
Xdoc.load (Xmlpath);
XmlNode XNode;
XmlElement xElem1;

XNode = Xdoc.selectsinglenode ("//appsettings");

XElem1 = (XmlElement) xnode.selectsinglenode ("//add[@key = '" + Appkey + "']");
if (xElem1!= null)
{
Appvalue=xelem1.getattribute ("value");
}
Else
{
MessageBox.Show ("There is isn't any information!");
}

}

#endregion