Implement Backspace button in Calculator MFC?

[greatman05]

First off, this is a homework assignment.

I am in a Software Engineering class and we're learning how to work with MFC. We're editing a basic calculator app. I don't know how to implement the backspace button (delete a single character from the edit box when the Backspace button is pressed). How is this done? I know that you can emulate character deletion with manipulation of char arrays in C++, but I don't know how you would do this with a number and in MFC. The application uses double integers.

[Ancient Dragon]

how are you catching keystrokes and writing to the window?

[greatman05]

The buttons are part of the message map. When the buttons are clicked, it sends the message to Windows which then writes the output to the edit box in the calculator (it's a dialog box).

[Ancient Dragon]

Now that I think about it I don't recall ever seeing a calculator with a backspace. They have a Clear button that erases the entire line so that you can re-enter the entire number.