C# : Anyone know how to fix this? : The type or namespace name 'T' could not be found

Question

Im really having trouble fixing my code, was wondering if there was anyone out there who could help me.

Basically im getting the following error:

The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?)

The following are my classes:

Program Class:

using System;
using System.Collections.Generic;
using System.Text;

namespace LinkedListGen

{
    class program
    {
        public static void Main(string[] args)
        {
            LinkListGen<T> testList = new LinkListGen<T>();
            Console.ReadKey();
        }
    }
}

LinkGen Class:

using System;
using System.Collections.Generic;
using System.Text;

namespace LinkedListGen
{
class LinkGen<T>
{
    private T data;
    private LinkGen<T> next;

    public LinkGen(T item)
    {
        data = item;
        next = null;
    }

    public LinkGen(T item, LinkGen<T> list)
    {
        data = item;
        next = list;
    }

    public LinkGen<T> TailList
    {
        set { this.next = value; }
        get { return this.next; }
    }

    public T HeadList
    {
            set { this.data = value; }
            get { return this.data; }
        }

    }
}

LinkListGen Class:

using System;
using System.Collections.Generic;
using System.Text;

namespace LinkedListGen
{
public class LinkListGen<T> where T : IComparable
{
    private LinkGen<T> list;

    public LinkListGen() //initialise list to be empty
    {
        list = null;
    }

    public void AddItem(T item)
    {
        list = new LinkGen<T>(item, list);
    }
    public string DisplayList() //write items to string
    {
        LinkGen<T> temp = list;
        string buffer = "";
        while (temp != null)
        {
            Console.WriteLine(temp.HeadList);
            temp = temp.TailList;
        }
        return buffer;
    }
    public int NumberOfItems()
    {
        LinkGen<T> temp = list;
        int count;
        count = 0;
        while (temp != null)
        {
            count++;
            temp = temp.TailList;
        }
        Console.Out.WriteLine("There are " + count + "items recorded.");
        return count;
    }

    public bool IsPresentItem(T item)
    {
        bool txf;
        LinkGen<T> temp = list;
        int count;
        count = 0;
        while (temp != null)
        {
            if (item.Equals(temp.HeadList))
            {
                count++;
            }
            temp = temp.TailList;
        }
        if (count > 0)
        {
            Console.Out.WriteLine("There are " + count + " instances of " + item + ".");
            txf = true;
        }
        else
        {
            Console.Out.WriteLine("There are no instances of " + item + ".");
            txf = false;
        }
        return txf;

    }

    public void RemoveItem(T item)
    {
        LinkGen<T> prev = list;
        LinkGen<T> curr = list;
        if (item.Equals(curr.HeadList))
            list = curr.TailList;
        else
        {
            while (curr != null)
            {
                if (item.Equals(curr.HeadList))
                {
                    prev.TailList = curr.TailList;
                }
                else
                {
                    prev = curr;
                    curr = curr.TailList;
                }
            }
        }
    }
}
}

The aim is to create a generic linked list

Im really at my wits end and would appreciate any help offered.

Answer 1

You have to specify a concrete type here, rather than the type placeholder, T:

    public static void Main(string[] args) 
    { 
        LinkListGen<T> testList = new LinkListGen<T>(); 
                    ^                             ^
        Console.ReadKey(); 
    } 

For example:

        LinkListGen<string> testList = new LinkListGen<string>(); 

Answer 2

LinkListGen<T> testList = new LinkListGen<T>();

You should replace 'T' here with the type you're trying to use for your generic list.