CS 205 - Programming for the Sciences
Spring 2008 - In-class Exercise for 01/17/08

Today's exercise is to finish the very simple (and stupid) RPN calculator by adding various types of error checking and a form of keyboard entry. We will look at if-statements in more detail, use a switch statement, and start looking at methods.

Assignment

(10 points) Working in pairs, add the following features to the calculator

• The initial value displayed should be 0.

• The backspace button should reset the display to 0 when the last digit is erased.

• When the input is 0, clicking the 0 button should have no effect.

• When the input is 0, clicking on any other digit should remove the 0. I.e., no leading 0.

• When new input is to be started and the first button clicked is dot, the display should read "0."

• When the current input contains a dot, clicking the dot button should have no effect.

• Add keyboard entry for digits, dot, Enter, and backspace.

We will work through the implementations of these features during class. When you are finished, demonstrate your program to an instructor.