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When writing/reading XML in vbScript, everything was easy because I could refer to nodes like an array (ex: main_node[0].sub_node[4]). I am learning C#, and am having problems with XML. All books and resources show me how to write a full file. What if I want to change the value of one element? Let's say I have the following XML file:

<person>
<name>Khelder</name>
<age>21</age>
</person>
<person>
<name>Redlehk</name>
<age>25</age>
</person>

Given the program knows the name "Redlehk", how would you go about reading in his age, and then writing back to the XML file a new age. If anyone can show me how this is done, or point me to a resource, I would greatly appreciate it.

Thanks,

Khelder

Here is one way to do it.

Suppose the XML file looks like this:

person.xml

Code:

<?xml version="1.0" encoding="UTF-8"?>
<persons xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<person>
		<name>Khelder</name>
		<age>21</age>
	</person>
	<person>
		<name>Redlehk</name>
		<age>25</age>
	</person>
</persons>

Then this will work:

Code:

using System;
using System.Xml;

namespace XmlTest
{
	class XmlTest
	{
		[STAThread]
		static void Main(string[] args)
		{
			// Load the Xml document
			XmlDocument xmlDoc = new XmlDocument();
			xmlDoc.Load("person.xml");

			// Create an XmlTextWriter from the document
			XmlTextWriter writer = new XmlTextWriter("person.xml", null);
			writer.Formatting = Formatting.Indented;

			// Loop through each person
			XmlNodeList personList = xmlDoc.GetElementsByTagName("person");
			for(int i = 0; i < personList.Count; i++)
			{
				XmlElement person = (XmlElement) personList[i];

				// Get the person's name
				XmlNodeList personNameList = person.GetElementsByTagName("name");
				XmlElement personName = (XmlElement) personNameList[0];

				// Get the person's age
				XmlNodeList personAgeList = person.GetElementsByTagName("age");
				XmlElement personAge = (XmlElement) personAgeList[0];

				// Compare the data
				if (personName.InnerText == "Redlehk")
					personAge.InnerText = "44";
			}

			// Write the changes
			xmlDoc.WriteContentTo(writer);
			writer.Flush();
			writer.Close();
		}
	}
}

Hope that helps.

David

That is exactly what I was looking for. Thank you. Ill try and implement it into my real project tonight, and I'll be back if I have some more questions.

Thanks again,

Khelder