Csharp/C Sharp by API/System/ConsoleModifiers

ConsoleModifiers.Alt

 
using System;
using System.Collections.Generic;
class MainClass
{
    public static void Main()
    {
        ConsoleKeyInfo key;
        List<char> input = new List<char>(); 
        do{
          key = Console.ReadKey(true);
          if (key.Key == ConsoleKey.F1)
          {
             Console.WriteLine("F1");
          }
          if (key.Key == ConsoleKey.Backspace)
          {
              if (input.Count > 0)
              {
                  input.RemoveAt(input.Count - 1);
                  Console.Write(key.KeyChar);
              }
          }else if (key.Key == ConsoleKey.Escape){
                Console.Clear();
                Console.WriteLine("Input: {0}\n\n",new String(input.ToArray()));
                input.Clear();
          }else if (key.Key >= ConsoleKey.A && key.Key <= ConsoleKey.Z){
                input.Add(key.KeyChar); 
                Console.Write(key.KeyChar);
           }
      } while (key.Key != ConsoleKey.X || key.Modifiers != ConsoleModifiers.Alt);
  }
}