Read a xml element and write back the new value of element to xml in C#

I am trying to read abc.xml which has this element

            <RunTimeStamp>
            9/22/2011 2:58:34 PM
            </RunTimeStamp>

I am trying to read the value of the element which the xml file has and store it in a string and once i am done with the processing. I get the current timestamp and write the new timestamp back to the xml file.

Here's my code so far, please help and guide, your help will be appreciated.

        using System;
        using System.Collections.Generic;
        using System.Linq;
        using System.Text;
        using log4net;
        using System.Xml;

        namespace TestApp
        {
            class TestApp
            {

                static void Main(string[] args)
                {

                    Console.WriteLine("\n--- Starting the  App --");

                    XmlTextReader reader = new XmlTextReader("abc.xml");

                    String DateVar = null;

                    while (reader.Read())
                    {
                        switch (reader.NodeType)
                        {

                            case XmlNodeType.Element: // The node is an element.
                                Console.Write("<" + reader.Name);
                                Console.WriteLine(">");
                                if(reader.Name.Equals("RunTimeStamp"))
                                {
                                    DateVar = reader.Value;
                                }
                                break;

                            case XmlNodeType.Text: //Display the text in each element.
                                Console.WriteLine(reader.Value);
                                break;

                            /*
                        case XmlNodeType.EndElement: //Display the end of the element.
                            Console.Write("</" + reader.Name);
                            Console.WriteLine(">");
                            break;
                             */
                        }
                    }
                    Console.ReadLine();

开发者_C百科                    // after done with the processing.
                    XmlTextWriter writer = new XmlTextWriter("abc.xml", null);

                }
            }
        }

I personally wouldn't use XmlReader etc here. I'd just load the whole file, preferrably with LINQ to XML:

XDocument doc = XDocument.Load("abc.xml");
XElement timestampElement = doc.Descendants("RunTimeStamp").First();
string value = (string) timestampElement;

// Then later...
timestampElement.Value = newValue;
doc.Save("abc.xml");

Much simpler!

Note that if the value is an XML-format date/time, you can cast to DateTime instead:

DateTime value = (DateTime) timestampElement;

then later:

timestampElement.Value = DateTime.UtcNow; // Or whatever

However, that will only handle valid XML date/time formats - otherwise you'll need to use DateTime.TryParseExact etc.

linq to xml is the best way to do it. Much simpler and easier as shown by @Jon