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Event Driven Programming

Fig. 14.4

14.3 Sample Project Specifications

We must build a form so that the user at the Order Desk can input a customer’s purchases. The
user will input the customer’s name and will select the customer’s city from a list of 5 cities that
will be shown to him. If the customer is from ‘Capital City’ he must pay 8% tax on his purchases
otherwise, there is no tax. The user will then input from 1 to 3 items that the customer purchased
along with the price of each item. The maximum price for an item is 50. Anything over that is
‘Too big’. If there is a price entered for an item there must be a description also. If an item is
being returned instead of purchased, the price will be negative and a red flag with the word
‘Credit’ will appear next to the price. When the user hits the ‘Calculate’ button, the subtotal, the
tax payable and the final total will appear. There must be the usual buttons to clear the form
and to exit when finished. There is also a need for a menu function to be able to cut, copy and
paste text from different parts of the form. The first thing to do is to create all the required
controls. However, because the items and the prices are a special case, don’t do them yet. This
form should look something like this:
14.4 Building a Calculator with Visual Basic

Microsoft Visual Basic is a programming language based on the BASIC language, originally
developed to make programming easier to learn. Visual Basic takes the familiar commands of
BASIC and adds object-oriented tools and interfaces for designing WYSIWYG-like Windows
applications and web controls, among many other enhancements. One relatively simple learning
project for Visual Basic is the creation of a Windows calculator.

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