Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

C# Foreach XML Node

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;
like image 308
Gio Borje Avatar asked Jan 27 '10 06:01

Gio Borje


People also ask

What C is used for?

C programming language is a machine-independent programming language that is mainly used to create many types of applications and operating systems such as Windows, and other complicated programs such as the Oracle database, Git, Python interpreter, and games and is considered a programming foundation in the process of ...

What is the full name of C?

In the real sense it has no meaning or full form. It was developed by Dennis Ritchie and Ken Thompson at AT&T bell Lab. First, they used to call it as B language then later they made some improvement into it and renamed it as C and its superscript as C++ which was invented by Dr.

Is C language easy?

Compared to other languages—like Java, PHP, or C#—C is a relatively simple language to learn for anyone just starting to learn computer programming because of its limited number of keywords.

What is C language?

C is an imperative procedural language supporting structured programming, lexical variable scope, and recursion, with a static type system. It was designed to be compiled to provide low-level access to memory and language constructs that map efficiently to machine instructions, all with minimal runtime support.


1 Answers

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");
IEnumerable<XElement> cords= xdoc.Descendants("coordinate");

var coordinates = cords
                  .Select(x => new Coordinate()
                                   {
                                      Time = x.Attribute("time").Value,
                                      Initial = x.Attribute("initial").Value,
                                      Final = x.Attribute("final").Value
                                    });

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

like image 50
marc_s Avatar answered Oct 23 '22 19:10

marc_s