# John David Ratliff's Online Resume Site

## Postfix Stack Calculator

#### Overview

This is a calculator which employs postfix notation and uses a stack to store its calculations. Postfix stack calculators and similar notational styles such as RPN, once learned, are much faster than using algebraic models.

Consider the following expression:

8 * 4 = 3

In Postfix, that would be 8 4 *.

Now, let's do a harder one:

2 + (3 * 8) - (4 + (48 / (4 + 2)) * 6)

We have to evaluate the parentheses first.

= 2 + 24 - (4 + (48 / 6) * 6) = 2 + 24 - (4 + 8 * 6) = 2 + 24 - (4 + 48) = 2 + 24 - 52 = -26

That is complicated for you and a calculator. Entering all the parentheses takes a lot of time. Consider the equivalent postfix notation.

2 3 8 * + 4 48 4 2 + / 6 * + -

How fast can you enter that last expression? I'm willing to bet it's much faster than you can find the parentheses for the first expression.

#### Features

• Postfix Style
• Any number of expressions.
• 10-position stack.
• Open Source
• Ant Build File.