Question

I’m learning how to make a linked list in c#. I have the below code which is not working for me. I just want to add the nodes in the main as i have below then iterate over all nodes that will print to the console.

using System;

class node
{
    public object data;
    public node next;

    public node()
    {
        data = null;
        next = null;
    }
    public node(object o)
    {
        data = o;
        next = null;
    }
    public node(object data, node next)
    {
        this.data = data;
        this.next = next;
    }    
}

class linkedList
{
    private node headNode;
    private node tailNode;

    int node_count;

    public void add(object entry)
    {
        if (headNode == null)
        {
            node newNode = new node(entry);
            headNode = newNode;
            ++node_count;
        }
        else
        {
            if (node_count == 1)
            {
                node newNode = new node(entry, headNode);
                tailNode = newNode;                
            }
            else 
            {
                node newNode = new node(entry, tailNode);
                tailNode = newNode;
            }
            ++node_count;
        }
    }

    public void returnData()
    {
        if (headNode.next != null)
        {
            while (headNode.next != null)
            { 
                Console.WriteLine(headNode.data + "\n");
            }
        }
        else
            Console.WriteLine("Not Available");
    }
}

class Exercise
{
    static int Main()
    {
        linkedList ll = new linkedList();
        ll.add(8);
        ll.add(2);
        ll.add(7);
        ll.add(4);
        ll.add(9);
        ll.add(10);

        ll.returnData();

        Console.ReadLine();
        return 0;
    }
}

Answer 1

Your code is completely broken.

Here’s minimal changes needed to run it

using System;

class node
{
    public object data;
    public node next;

    public node()
    {
        data = null;
        next = null;
    }
    public node(object o)
    {
        data = o;
        next = null;
    }
    public node(object data, node next)
    {
        this.data = data;
        this.next = next;
    }    
}

class linkedList
{
    private node headNode;
    private node tailNode;

    int node_count;

    public void add(object entry)
    {
        node newNode = new node(entry);
        if (headNode == null)
            headNode = newNode;
        if (tailNode != null)
            tailNode.next = newNode;
        tailNode = newNode;
        ++node_count;
    }

    public void returnData()
    {
        node currentNode = headNode;

        if (currentNode == null)
            Console.WriteLine("Not Available");

        while (currentNode != null) {
            Console.WriteLine(currentNode.data);
            currentNode = currentNode.next;
        }

    }
}

class Exercise
{
    static int Main()
    {
        linkedList ll = new linkedList();
        ll.add(8);
        ll.add(2);
        ll.add(7);
        ll.add(4);
        ll.add(9);
        ll.add(10);

        ll.returnData();

        return 0;
    }
}