How can I make it write to a file when pressing backspace?

Question

C++ / C#

How to make that when you press backspace, there would be a write to a file in c #?
On c# console

Answer 1

var key = Console.ReadKey();
if(key == ConsoleKey.Backspace)
  WriteDataToFile();

Answer 2

The right question is 50% of the answer. Which app? Console, wpf, uwp, winforms?