C# Object Linked List

millsbruce · July 11th, 2005, 01:10 PM

Can anyone guide me in the right direction on use of linked lists in C#. Is there a .NET object to handle this now. I have developed linked lists in C / Visual C++. Typically, I have an object containing a next pointer and a previous pointer to the same type of object. A linked list manager object exists to provide a interface for the list. The user can add and delete dynamically.

Do I need to look at unsafe objects due to the pointers ? What is the Collection object in .NET ? Is that similair to my linked lists in C ??

Any help would be appreciated !

BMM

Doknjas · July 11th, 2005, 08:30 PM

There's no built-in .NET class for this, but you can do this with nested classes without pointers:

public class LinkedList
{
    public class Node
    {
        internal object MyData;
        internal int Next;
        internal int Previous;
    }
    private ArrayList MyList = new ArrayList();
    //methods to add, remove, etc.
}

jacob · July 12th, 2005, 08:55 AM

Just use the ArrayList; I am pretty sure that it basically is implemented as a linked list, and there are methods for moving around in the list so therefore you should not need the next and previous pointers.

There are Add and Remove methods in the ArrayList class. Here is some example code...

Code:

ArrayList list = new ArrayList();

list.Add("something");
list.Add("somethingelse");

IEnumerator i = list.GetEnumerator();
while(i.MoveNext())
    Console.WriteLine(i.Current);

if(list.Count > 0)
    Console.WriteLine(list[0]);

Hope it helps, Jacob.

Doknjas · July 12th, 2005, 11:04 AM

D'oh...

You're right Jacob - here I was getting too complicated - ArrayList does indeed seem to stand on its own as a LinkedList.

millsbruce · July 12th, 2005, 02:28 PM

How does ArrayList handle a delete of an object in the middle of the list ? It appears to still be an array ? Am I still chewing up memory for the array, even tough I may have deleted objects . Is it dynamic in memory use ?

jacob · July 12th, 2005, 04:15 PM

Hey, I just did some experiments with ArrayList, but I didn't know how to see if the memory is deallocated. However, I am quite sure that memory is deallocated, since when an item is removed in the list the items shift index; i.e. it is reduced in size. In C# you do not have to think about allocation/deallocation directly as in C.

Jacob.