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Using Linked List in C#

By Jay Smith on Jun 25, 2003
What we going to make is a linked list. Yeah I know there is a class which does the same as a linked list called ArrayList, but we (as a diehard C# programmer) want absolute control and knowledge of what we use.

What we going to make is a linked list. Yeah I know there is a class which does the same as a linked list called ArrayList, but we (as a diehard C# programmer) want absolute control and knowledge of what we use.

First what is a linked list?

A linked list is a dynamically sized array. An array has a size and you have to deal with it you cant just resize an array. Unlike an array a linked list has no absolute size. It can hold as many variables as you want it to.

When to use?

In circumstances where you dont know how many variables you want to add. For example it could be just 1 or it could be 1000. In such a situation its stupid to make an array of 10000 it would be a waist of memory.

Now a design of our classes LinkedList and Node.

Note: Prefix i is for an integer and a prefix n is for a Node.

In the Node class there is a Previous and a Next Node. Because of that all Nodes are linked to eachother (thats why they called it a linkedlist).

Here is the Node class

public class Node
{
protected Node nPrevious;
protected Node nNext;
protected object Object;
#region Properties
public object Value
{
get
{
return Object;
}
set
{
Object =
value;
}
}
public Node Previous
{
get
{
return nPrevious;
}
set
{
nPrevious =
value;
}
}
public Node Next
{
get
{
return nNext;
}
set
{
nNext =
value;
}
}
#endregion
public Node(Node PrevNode, Node NextNode, object obj)
{
nPrevious = PrevNode;
nNext = NextNode;
Object = obj;
}
}

As you can see there isnt much of a surprise
if you studied the class design.

Next thing the LinkedList class.

public class LinkedList
{
int iCount = 1;
int iCurrent = 0;
Node nCurrent;
#region Properties
/// <summary>
/// Give back how many nodes there are.
/// </summary>
public int Count
{
get
{
return iCount;
}
}
/// <summary>
/// Gives back the current Node
/// </summary>
public Node CurrentNode
{
get
{
return nCurrent;
}
}
/// <summary>
/// Keeps track of the index where you are
/// </summary>
public int CurrentNodeIndex
{
get
{
return iCurrent;
}
}
#endregion
/// <summary>
/// Default and only Constructor
/// SetUp our LinkedList
/// </summary>
/// <param name="obj">Value for the first Node</param>
public LinkedList(object obj)
{
nCurrent =
new Node(null, null, obj);
nCurrent.Next =
null;
nCurrent.Previous =
null;
}
/// <summary>
/// This function will add another Node
/// </summary>
/// <param name="obj">Value for the added Node</param>
public void AddNode(object obj)
{
if(nCurrent.Next == null)
{
nCurrent = nCurrent.Next =
new Node(nCurrent, null, obj);
}
else
{
nCurrent = nCurrent.Next =
new Node(nCurrent, nCurrent.Next,obj);
}
iCount++;
iCurrent++;
}
/// <summary>
/// Goes to the next Node
/// </summary>
public void ToNext()
{
// Checks whether the Next Node is null
// if so it throws an exception.
// You can also do nothing but I choos for this.
if(nCurrent.Next == null)
{
throw new Exception("There is no next node!");
}
else // If everything is OK
{
nCurrent = nCurrent.Next;
iCurrent++;
}
}
/// <summary>
/// Goes to the previous Node
/// </summary>
public void ToPrevious()
{
// Look at ToNext();
if(nCurrent.Previous == null)
{
throw new Exception("There is no previous node!");
}
else
{
nCurrent = nCurrent.Previous;
iCurrent--;
}
}
/// <summary>
/// Goes to the index you fill in
/// </summary>
/// <param name="index">Index Where to go?</param>
public void GoTo(int index)
{
if(iCurrent < index)
{
ToNext();
}
else if(iCurrent > index)
{
ToPrevious();
}
}
}

Conclusion:

It isnt hard to make a linked list and I guess most programmers are already familiar with linked lists. And for the C++ programmers out there you see without pointers :p ( I just hate pointers)