I have used Visual Studio 2012 for debugging purpose. But you can use any version of visul studio as per your availability..

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
public class csharpExercise
{
    static void Main(string[] args)
    {
        int num, sum = 0, i, r;
 
        // Reading number
        Console.Write("Please enter a number: ");
        num = Convert.ToInt32(Console.ReadLine());
 
        //Finding armstrong number or not
        for (i = num; i > 0; i = i / 10)
        {
            r = i % 10;
            sum = sum + r * r * r;
        }
 
        if (num == sum)
        {
            Console.WriteLine(num + " is an armstrong number.");
        }
        else
        {
            Console.WriteLine(num + " is not an armstrong number.");
        }
 
        Console.ReadLine();
    }
}

Result:

Please enter a number: 407

407 is an armstrong number.