如果值增加阈值，则读取XML的特定元素

Question

I can read an XML file named 101.xml in which I can read element named light having two values say 1280 and 128, I can display it. But I want to display only that value which is greater than 800. Check image for XML file.

This is what I did to read both light elements in Listbox:

READING NEW FILE:

        XmlTextReader Reader = new XmlTextReader(@"101.xml");
        XmlDocument doc = new XmlDocument();
        doc.Load(Reader);
        XPathNavigator nav = doc.CreateNavigator();

        //compile xpath 
        XPathExpression expr;
        expr = nav.Compile("/MotePacket/ParsedDataElement[Name='light']");
        XPathNodeIterator iterator = nav.Select(expr);

        //iterate node set and see values in list box
        listBox1.Items.Clear();
        try
        {
            while (iterator.MoveNext())
            {
                XPathNavigator nav2 = iterator.Current.Clone();
                listBox1.Items.Add("content and value: " + nav2);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

Answer 1

This is very bad xml format. Recommend changing. Here is code to parse xml

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

namespace ConsoleApplication1
{
    class Program
    {
        const string FILENAME = @"c:\temp\test.xml";
        static void Main(string[] args)
        {
            XDocument doc = XDocument.Load(FILENAME);

            List<XElement> parsedDataElements = doc.Descendants("ParsedDataElement").ToList();

            for (int i = 0; i < parsedDataElements.Count; i += 2)
            {
                DataElement newDataElement = new DataElement();
                DataElement.elements.Add(newDataElement);

                newDataElement.temperature = (double)parsedDataElements[i].Element("ConvertedValue");
                newDataElement.light = (int)parsedDataElements[i + 1].Element("ConvertedValue");
            }
        }
    }
    public class DataElement
    {
        public static List<DataElement> elements = new List<DataElement>();

        public double temperature { get; set; }
        public int light { get; set; }
    }
}

Answer 2

As i mentioned in the comment to the question, you can use XDocument class together with Linq query to filter xml data.

See:

XDocument xdoc = XDocument.Load(fullfilename);

var data = xdoc.Descendants("ParsedDataElement")
    .Where(x=>x.Element("Name").Value == "light" && Double.Parse(x.Element("ConvertedValue").Value)>800)
    .Select(x=> new
    {
        Name =  x.Element("Name").Value,
        ConvertedValue = Double.Parse(x.Element("ConvertedValue").Value)
    })
    .ToList();

Now, you are able to insert data into ListBox object by using foreach loop or by setting DataSource .

For further details, please see:
Basic Queries (LINQ to XML) (C#)
How to: Bind a Windows Forms ComboBox or ListBox Control to Data

Good luck!