using System;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            while(true)
            {
                Console.Clear();
                Console.WriteLine("Press 1 or 2 to perform operation. Press any other key to exit");
                Console.WriteLine("1. All digits from highest to lowest using while");
                Console.WriteLine("2. All digits from highest to lowest using for");

                var key = Console.ReadKey();

                if (key.Key == ConsoleKey.D1)
                {
                    DigitsUsingWhile();

                }
                else if (key.Key == ConsoleKey.D2)
                {
                    DigitsUsingFor();
                }
                else
                {
                    return;
                }
            }
        }

        static void DigitsUsingWhile()
        {
            Console.Clear();
            Console.WriteLine("Writing digits from highest to lowest using while loop");

            int i = 9;
            while(i >= 0)
            {
                Console.WriteLine(i);
                i--;
            }

            AfterLoop();
        }

        static void DigitsUsingFor()
        {
            Console.Clear();
            Console.WriteLine("Writing digits from highest to lowest using for loop");

            for (int i = 9; i >= 0; i--)
            {
                Console.WriteLine(i);
            }

            AfterLoop();
        }

        static void AfterLoop()
        {
            Console.WriteLine("Press any key to return to menu");
            Console.ReadKey();
        }
    }
}