XML Navigation

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