C# | Creating a read-only wrapper for the List

// C# code to create a read-only
// wrapper for the List<T>
using System;
using System.Collections;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an List<T> of Integers
        List<int> firstlist = new List<int>();

        // Adding elements to List
        firstlist.Add(1);
        firstlist.Add(2);
        firstlist.Add(3);
        firstlist.Add(4);
        firstlist.Add(5);
        firstlist.Add(6);
        firstlist.Add(7);

        Console.WriteLine("Before Wrapping: ");

        // Displaying the elements in the List
        foreach(int i in firstlist)
        {
            Console.WriteLine(i);
        }

        // Creating a Read-Only packing
        // around the List<T>
        IList<int> mylist2 = firstlist.AsReadOnly();

        Console.WriteLine("After Wrapping: ");

        // Displaying the elements
        foreach(int m in mylist2)
        {
            Console.WriteLine(m);
        }

        Console.WriteLine("Trying to add new element into mylist2:");

        // it will give error
        mylist2.Add(8);
    }
}