C# Foreach XML Node

Question

I'm saving 2-dimensional coordinates on an XML file with a structure similar to:

<?xml version="1.0" encoding="utf-8" ?> 
<grid>
<coordinate time="78">
<initial>540:672</initial> 
<final>540:672</final> 
</coordinate>
</grid>

I can open the XML file and read it via the XmlTextReader, but how do I loop through the coordinates specifically to retrieve both the time attribute and data between the initial and final nodes in some format similar to:

string initial = "540:672";
string final  = "540:672";
int time = 78;

---

New Code:

My New Code:

//Read the XML file.
XDocument xmlDoc = XDocument.Load("C:\\test.xml");

foreach (var coordinate in xmlDoc.Descendants("coordinate"))
{
    this.coordinates[this.counter][0] = coordinate.Attribute("time").Value;
    this.coordinates[this.counter][1] = coordinate.Element("initial").Value;
    this.coordinates[this.counter][2] = coordinate.Element("final").Value;
    this.counter++;
};

but now I get this error:
"Object reference not set to an instance of an object."

---

XML

<?xml version="1.0" encoding="utf-8"?>
<grid>
  <coordinate time="62">
    <initial>540:672</initial>
    <final>540:672</final>
  </coordinate>

  ...

  <coordinate time="46">
    <initial>176:605</initial>
    <final>181:617</final>
  </coordinate>
</grid>

Skipped a few coordinate tags to fit, but they all had the time attribute and initial/final subtags.

---

Globals

uint counter = 0;

        // Coordinates to be retrieved from the XML file.
        string[][] coordinates;

Answer 1

You might want to check into something like Linq-to-XML:

XDocument coordinates = XDocument.Load("yourfilename.xml");

foreach(var coordinate in coordinates.Descendants("coordinate"))
{
    string time = coordinate.Attribute("time").Value;

    string initial = coordinate.Element("initial").Value;
    string final = coordinate.Element("final").Value;

    // do whatever you want to do with those items of information now
}

That should be a lot easier than using straight low-level XmlTextReader....

See here or here (or a great many other places) for introductions to Linq-to-XML.

---

UPDATE:

please try this code - if it works, and you get all the coordinates in that resulting list, then the Linq-to-XML code is fine:

Define a new helper class:

public class Coordinate
{
    public string Time { get; set; }
    public string Initial { get; set; }
    public string Final { get; set; }
}

and in your main code:

XDocument xdoc = XDocument.Load("C:\\test.xml");

List<Coordinate> list = new List<Coordinate>();

foreach (var coordinate in xdoc.Descendants("coordinate"))
{
    string time = coordinate.Attribute("time").Value;
    string initial = coordinate.Element("initial").Value;
    string final = coordinate.Element("final").Value;

    list.Add(new Coordinate { Time = time, Initial = initial, Final = final });
}

How does this list and its contents look like?? Do you get all the coordinates you're expecting??

Answer 2

You could have used XmlSerialization to make the XML into a simple list of coordinate classes with a small amount of work, e.g.

    public class coordinate
    {
        [XmlAttribute]
        public int time;
        [XmlElement(ElementName="initial")]
        public string initial;
        [XmlElement(ElementName = "final")]
        public string final;

        public coordinate()
        {
            time = 0;
            initial = "";
            final = "";
        }
    }

    public class grid
    {
        [XmlElement(ElementName="coordinate", Type = typeof(coordinate))]
        public coordinate[] list;

        public grid()
        {
            list = new coordinate[0];
        }
    }     

Then in your code:

XmlReader r = new XmlReader.Create(...);
grid g = (grid) new XmlSerializer(typeof(grid)).Deserialize(r);