Data structure (tree)

[csharpula csharp]

Hello friends,
I would like to know what is the best way to store a tree structure in
c#? Are there any good implementation examples for seing how to do it?

Thank u!

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[Peter Duniho]

On Mon, 05 May 2008 09:26:49 -0700, csharpula csharp <cs*******@yahoo.com>
wrote:

I would like to know what is the best way to store a tree structure in
c#?

That depends on the nature of the tree. However, it's simple enough to
write your own class that maintains a tree in whatever manner is
appropriate for your data. Common tree implementations would include
references to children either via a fixed number of instance fields (e.g.
binary tree) or an instance field that holds a reference to a collection
of child nodes (e.g. a List<Tinstance containing all the children for
that node).

Are there any good implementation examples for seing how to do it?

A number of Framework classes use tree-like collections. You certainly
could examine them to learn more about different .NET implementations that
exist. For example, the Control class (Control.Controls), the TreeView
class (TreeView.Nodes, and TreeNode.Nodes), and the generic SortedList<T>
class, to name a few.

Pete

[csharpula csharp]

The question is what is the best way to implement a tree structure which
will store the deserialization result of xml structure which represents
a tree. what is the best way? is there any class that already implements
that?

Thank u very much!
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[Marc Gravell]

Since you are working with xml, would XmlDocument or XDocument suffice?

Marc

[csharpula csharp]

But I want to represent a tree in a c# class not via xml ,the result of
xml deserialization will be the data of this class. how to do it? thank
u!
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[Marc Gravell]

It depends; if you know what the data looks like in advance, then fine -
use XmlSerializer to read the xml into your class structure. But this
won't work for ad-hoc xml.

Example below - is this what you had in mind? If not - please explain
what you do want...

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
[Serializable]
public sealed class TreeNode
{
[XmlAttribute]
public string Key { get; set; }
[XmlAttribute]
public string Text { get; set; }

private List<TreeNodenodes;

public List<TreeNodeNodes
{
get
{
if(nodes == null) nodes = new List<TreeNode>();
return nodes;
}
}

public override string ToString()
{
return Text;
}
}

static class Program {
static void Main() {
TreeNode tree = new TreeNode {
Key = "A", Text = "Foo",
Nodes = {
new TreeNode
{
Key = "B", Text = "Bar",
Nodes = {
new TreeNode {
Key = "C", Text = "Blip"
}
}
},
new TreeNode {
Key = "D", Text = "Blop"
}
}
};
StringBuilder sb = new StringBuilder();
XmlSerializer xser = new XmlSerializer(typeof(TreeNode));
using (XmlWriter writer = XmlWriter.Create(sb))
{
xser.Serialize(writer, tree);
writer.Close();
}

string xml = sb.ToString();
Console.WriteLine(xml);

using (XmlReader reader = XmlReader.Create(new StringReader(xml)))
{
TreeNode backAgain = (TreeNode) xser.Deserialize(reader);
}
}
}

[Marc Gravell]

re-hacked in case you are using C# 2 - actually it is more readable this
way, too...

added 2 .ctor()s for TreeNode:

public TreeNode() : this("","") { }
public TreeNode(string key, string text,
params TreeNode[] nodes)
{
Key = key;
Text = text;
if (nodes != null && nodes.Length 0)
{
Nodes.AddRange(nodes);
}
}

and changed demo setup code:

TreeNode tree = new TreeNode("A", "Foo",
new TreeNode("B", "Bar",
new TreeNode("C", "Blip")
),
new TreeNode("D", "Blop")
);

Same result, just done differently...

Marc

[csharpula csharp]

But my question is if I need to create the TreeNode class by myself and
implement all the tree functionality or I can use some pre defined class
or implment some tree template interface?
Thanks!
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[Marc Gravell]

csharpula csharp wrote:

But my question is if I need to create the TreeNode class by myself and
implement all the tree functionality or I can use some pre defined class
or implment some tree template interface?
Thanks!

To come back full-circle, XmlDocument is a fully-functional pre-defined
class for loading an arbitrary tree of data... if you want something in
between, you're going to have to be a lot more specific about what you
want (and probably write it yourself).

In System.Web.UI, there are some interfaces - IHierarchyData,
IHierarchicalEnumerable, IHierarchicalDataSource - but to be honest I
wouldn't worry unless you are using the web tree-view.

Marc