Modifying the web.config file from a windows application

In this article, we are going to see how we can modify the web.config file of an asp.net application using a windows based application in C#.

In this code sample, we are following the below steps:

1.First get the path where the web.config file is located on our system. Here we are updating the config file which is located in "c:\inetpub\WWWRoot\WebSite1" location.
2.Then using XmlDocument class load the file in memory.
3.Get the reference to the appSettings section, with key=ipaddress.
4.if we can find the node with above key, then change its value to the value entered by the user in the textbox and save back the file.
5.In case of any exceptions, display it in a messagebox.

  //Get the path of the web.config file of the application which you want to modify
            string filename = @"c:\inetpub\WWWRoot\WebSite1\Web.Config";
            try
            {
                System.Xml.XmlDocument Doc = new System.Xml.XmlDocument();
                //Load the config file in memory.
                Doc.Load(filename);
                System.Xml.XmlElement Root = Doc.DocumentElement;

                //Get the node which contains the appsettings section with key "ipaddress"
                string xpath = "appSettings/add[@key='ipaddress']";
                System.Xml.XmlNode xnode = Root.SelectSingleNode(xpath);
                if (xnode != null)
                {
                    //update the key "ipaddress" with the value entered in the textbox by the user.
                    xnode.Attributes["value"].Value = txtIpAddress.Text;
                }
                //Save the config file.
                Doc.Save(filename);
            }
            catch (System.Exception ex)
            {
                //Incase of any exception, display it in a message box.
               MessageBox.Show(ex.Message);
            }