using System;

using System.Collections.Generic;

using System.Linq;

using System.Dynamic;

​

public class Program

{

    public static void Main()

    {

        //You can perform an action on the element passed to the Action delegate in ForEach

        //but you cannot replace it with a new value

        var nums = new List<int>{1, 2, 3};

        nums.ForEach(x => x++);

        foreach (var thisNum in nums)

        {

            Console.WriteLine(thisNum);

        }

​

        Console.WriteLine("-------Above does not work------");

        foreach (var thisNum in nums)

        {

        //thisNum++; // <== will not compile

        }

​

        for (int i = nums.Count - 1; i >= 0; i--)

        {

            nums[i]++;

        }

​

        Console.WriteLine("-------Below works--------------");

        foreach (var thisNum in nums)

        {

            Console.WriteLine(thisNum);

        }

    }

}