CODEWITHSUNDEEP
c#
Tomo
Tomo

Reputation: 27

C#, SingleLinkedList question about while loop

I have few questions...

So I'm working with Single Linked List and I have some issues understanding the code. So let's say I have something like this: 

            public void addToEnd(int data)
        {
            Node p = start;

            Node temp = new Node(data);

            if (start == null)
            {
                start = temp;
                return;
            }
            else
            {
                while(p.link != null)
                {
                    p = p.link;
                }

                p.link = temp;

            }
        }

So... This code will add Node at the end of the list. I get that. Let's check the display list method...

 public void displayList()
        {
            Node p = start;

            if (start == null)
            {
                Console.WriteLine("List is empty.");
                return;
            }

            while(p != null)
            {

                Console.Write("|" + p.data + "| -> ");
                p = p.link;

            }

        }

So my concern is this... In displayList method, while loop says - ( while p != null ) ... I played with it a bit, and I changed it into - ( while p.link != null ). So result is that it wont print last element of the list. And so I got to conclusion that p.link is not last Node, but one before. It is just referring to the last Node of the list. So if my assumption is correct, how come that method addToEnd(int data) is working perfectly, and it's really adding some Node to the end if the wile loop in that method is - ( while p.link != null ). Shouldn't it like in case of displayList() method when I change the while loop point to the second last element of the list? If someone can explain this one to me that would be amazing. Thanks in advance guys ;)

Upvotes: 0

Views: 53

Answers (1)

PedroC88
PedroC88

Reputation: 3829

Both methods are correct, let's break down the elements:

  1. addToEnd will add an element to the end of the linked list
  2. displayList prints the whole list with format |{int}|->
  3. start seems to be a class level Node that defines the first element of the list
  4. The Node class has a Link property that links the next Node on the list (not the last)

Now, how does displayList work?

  1. Declare a p variable that will have the node that the method is working with at any given time
  2. Check if p, now that it's being assigned the start node, is empty, if it's empty a message is shown and the method ends, then
  3. While p (the current element) is not null, print its value and then assign to p the next element on the list, which is p.Link
  4. If the next element is null, the while exists and that's the end

The difference between the two methods is that addToEnd checks if the next node is null to assign data as the last element. displayList can't move to the next element until it has printed the current one.

Upvotes: 1

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