Book Image

Visual Basic Quickstart Guide

By : Aspen Olmsted
Book Image

Visual Basic Quickstart Guide

By: Aspen Olmsted

Overview of this book

Whether you’re an absolute beginner or an experienced developer looking to learn the Visual Basic language, this book takes a hands-on approach to guide you through the process. From the very first chapters, you'll delve into writing programs, exploring core concepts such as data types, decision branching, and iteration. Additionally, you’ll get to grips with working with data structures, file I/O, and essential object-oriented principles like inheritance and polymorphism. This book goes beyond the basics to equip you with the skills to read and write code across the entire VB family, spanning VB Script, VBA, VB Classic, and VB.NET, enabling you to handle legacy code maintenance with ease. With clear explanations, practical examples, and hands-on exercises, this book empowers you to tackle real-world software development tasks, whether you're enhancing existing projects or embarking on new ones. It addresses common challenges like distinguishing between the variations of the VB programming language to help you choose the right one for your projects. Don't let VB's extensive legacy daunt you; embrace it with this comprehensive guide that equips you with practical, up-to-date coding skills to overcome the challenges presented by Visual Basic's rich history of over two decades.
Table of Contents (27 chapters)
Free Chapter
1
Part 1:Visual Basic Programming and Scripting
9
Part 2:Visual Basic Files and Data Structures
14
Part 3:Object-Oriented Visual Basic
20
Part 4:Server-Side Development

Building the project in VBA

What follows is VBA code for a simple calculator that allows the user to enter two numbers and an operator and then perform the corresponding arithmetic operation on the two numbers.

The code initializes some variables and then enters a Do-While loop allows the user to perform multiple calculations until they choose to quit. Within the loop, the code displays input boxes for the user to enter the first, second, and operator numbers.

After the user enters the values, the code uses a Select Case statement to check which operator was entered and perform the corresponding calculation. If the user enters an invalid operator or attempts to divide by zero, the code displays a message box with an error message. The result is displayed in a message box if the calculation is successful.

The loop continues until the user enters X to quit, at which point the sentinel variable is set to True, and the loop ends:

Option Explicit
Sub VBACalc()
Dim n1, n2, res...