LinkList.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;

namespace LinkedList
{
    public class LinkedListGen<T> where T:IComparable<T>
    {
        private NodeGen<T> head;

        public LinkedListGen()
        {
            head = null;
        }

        public void AddToHead(T item) //newnode.next make sure head isn't lost. 
        {
            NodeGen<T> newNode = new NodeGen<T>(item);
            if (head == null)
            {
                head = newNode;
                return;
            }
            newNode.Next = head;
            head = newNode;
        }

        public string DisplayItems()
        {
            NodeGen<T> temp = head;
            string buffer = " ";

            while(temp != null)
            {
                if (buffer.Length == 0)
                {
                    buffer = buffer + temp.Data;
                } else
                {
                    buffer = buffer + "->" + temp.Data;
                    temp = temp.Next;
                }
            }
            return buffer; 
        }

        public int NumberOfItems()
        {
            NodeGen<T> temp = head;
            int count = 0;

            while (temp != null)
            {
                count++;
                temp = temp.Next;
            }
            return count;
        }

        public void AddToIndex(T element, int index)
        {
            NodeGen<T> temp = head;
            NodeGen<T> newNode = new NodeGen<T>(element);

            for (int i = 1; i < index -1; i++)
            {
                temp = temp.Next;
            }
            newNode.Next = temp.Next;
            temp.Next = newNode;
        }

        public LinkedListGen<T> RemoveItem(T item)
        {
            NodeGen<T> temp = head;
            LinkedListGen<T> newList = new LinkedListGen<T>();

            while(temp != null)
            {
                if (item.CompareTo(temp.Data) != 0)
                {
                    newList.AppendItem(temp.Data);
                    temp = temp.Next;
                }
            }
            return newList; 
        }

        public void AppendItem(T item)
        {
            NodeGen<T> temp = head; 
            NodeGen<T> newNode = new NodeGen<T>(item);
            
            if (head == null)
            {
                head = newNode;
                return;
            }
            
            while(temp.Next != null)
            {
                temp = temp.Next; 
            }
            temp.Next = newNode;
        }

        public bool IsPresent(T item)
        {
            NodeGen<T> temp = head; 
            while (temp != null)
            {
                if (temp.Data.CompareTo(item) == 0)
                {
                    return true;
                } else
                {
                    temp = temp.Next;
                }
            }
            return false; 
        }
    }
}