Objective for this step

In this step, we will put in all the core business logic. At the end of this step, you will have a fully functional calculator.

By "core", we mean it will function, provided the user don't key in anything funny, such as "1.2.3 * + 456". We will put in the validation checks in Step 3.

The Steps

To make the codes easier to understand, and to "similulate" the actual process when developing a php-gtk application, we will break this down into a number of sub-steps. At each step, you will always have a fully runnable script - that's the beauty of a script language!

2.1 Process the numbers

2.2 Process the binary operators (+-*/) and equal sign (=)

2.3 Process the unary operators: sqrt, %, 1/x and +/-

2.4 Process the rest of the buttons

We will first process just the button clicks first, then move on to process keyboard inputs.

2.5 Process keyboard inputs

Links

• Calculator Main Menu
• Step 1: Layout the widgets
• Step 3: Validation Checks
• Step 4: Improve on User Interface