Visual Basic

This book is written from a Visual Basic 6.0 perspective although much of what is said is also valid for Visual Basic 5.0 and Visual Basic 4.0. This book does not cover VB.NET which is in fact a radically different language. It covers many different techniques and topics including optimization of programs, object oriented programming and coding guidelines to name a few. To assist readers in getting started several complete applications of varying degrees of sophistication are presented in the Case Studies chapter.

Introduction

This book's sole purpose is to help people better understand Visual Basic.

History

A timeline of Visual Basic's history.

Getting Started

VB6 IDE (Integrated Development Environment) is highly useful for developing GUI (Graphical User Interface) applications.

Simple Arithmetic

Introduction to calculating and operands with Visual Basic.

Branching

Branching occurs when the program makes a decision. The flow of execution follows a particular branch like a fork in the road.

Loops

Loops are control structures used to repeat a given section of code a certain number of times or until a particular condition is met.

Strings

Strings hold printable characters. They are very useful for communicating with human beings and for transferring data between programs and machines in text files and web pages.

Arrays

Arrays are used to group data items of the same type together, to make it easier to search and sort through this data.

User Interfaces

A user interface is the part of your program that is visible to a human user. It can be as simple as a DOS command line or as sophisticated as an immersive virtual reality simulator. However, in the context of Visual Basic it usually means what is commonly referred to as a Graphical User Interface or GUI which generally consists of one or more Forms that contain text boxes, labels, buttons, picture boxes, etc.

Simple Graphics

Visual Basic can easily be used to draw simple graphics such as line drawings and diagrams.

Files

While programming, you may want to at some point save data so they may be accessible for further use. This is where file I/O comes in. Visual Basic allows us to perform most operations available in Windows Explorer and DOS command line.

Data Types

A datatype is a specification of the kind of information that a variable can hold, for example, a number or a piece of text.

Procedures and Functions

A function is a calling procedure or small part of a program that performs some specific task and returns a result; for example the cosine function.

Windows Dialogs

Windows dialogs are useful when one requires standard interfaces, including opening files, saving files, choosing color and/or font, specifying printer settings.

Databases

Visual Basic can connect to databases in many different ways.

Windows API

APIs, short for "application programming interface", allows you to access a wide array of functions and methods exposed by the operating system or other applications (DLLs), performing operations not normally implemented by the standard virtual machine that Visual Basic provides.

Subclassing

Visual Basic hides the details of all the messages that Windows sends to an application but you can get at them if you really need to. Then you can do things that plain Visual Basic cannot.

External Processes

Sometimes you want to call another program from Visual Basic.

Object Oriented Programming

There is a lot of complicated talk about Object Oriented Programming but in essence it is quite simple.

Effective Programming

It isn't enough that the program work, you must be able to maintain it as well. Effective programmers can read their code as well as write it.

Idioms

An idiom is a sort of template or generic method of expressing an idea. In the same way that idioms in a human language make life easier for the both speaker and listener good idioms in computer programming make life easier for the programmer. Naturally what is idiomatic in one language might not be in another.

Optimizing Visual Basic

Once your program is up and running and producing correct results you might want to consider optimizing it. This means making it run faster or use fewer or less expensive resources. As you gain experience you will recognize that some programming idioms produce better results than others under some circumstances. Being able to recognize these situations will enable you to choose the best method straight away.

Examples

This section contains a number of ready made code examples for your use. They vary from short snippets to complete modules and short demo applications.

• Regular Expression Tester: A small, almost throwaway application that demonstrates that useful application do not need to be either large or complicated.
• JArithmetic

The Language

This section summarizes the syntax of Visual Basic and describes all the key concepts that of Visual Basic. It also notes some features that exist in other languages but do not exist in Visual basic.

Coding Standards

Consistent style in coding helps everyone to maintain a program whether the maintainer is the original author or not.

Selected Functions

Short descriptions of some of the functions that are used in this book.

VB6 Command Reference

This section serves as guide to the commands that can be used in Visual Basic.

Glossary

Brief explanations of various important, difficult or otherwise interesting words and phrases with links to longer explanations in the body of the text.

Work in Progress

Various unfinished pages. Please look here for anything obscure or difficult.

Related Works

Anyone who is serious about the art of programming should know about more than one language and should also be conversant with the foundations of computing. As mentioned in the Idioms chapter you can borrow ideas from other languages even if the language you use appears not to support them. Here is a list of suggested works, some on-line some in print.

Donald Knuth

The Art of Computer Programming. Knuth's masterpiece, let's hope he lives long enough to complete it.

Data Structures

Programs operate on data so knowledge of effective data structures is very important.

Algorithms

Many algorithms were described long before computers were available and many have both naive inefficient forms and sophisticated efficient forms. In many cases this is independent of the implementation language.

Object Oriented Programming

External Links

Link	Comment
Visual Basic Tutorial	37 Lessons on Visual Basic 6 and sample source code
Visual Basic 6 (VB6) tutorials and source code	Example Visual Basic 6.0 tutorials and source code
VBCorLib	Do exceptions in Visual Basic 6.0
Visual Basic Tutorials
WinsockVB	Everything there is to know about sockets and Visual Basic 6.0. Still has active forums. OFF LINE
VBSpeed	Objective evidence you can use to help you write faster code
GPWiki	Contains more game related Visual Basic tutorials
XtremeVBTalk	A VB forum
AllAPI	Examples for Windows APIs
Hardcore Visual Basic	Bruce McKinney's masterpiece; shows that you can write almost anything in Visual Basic 6.0.
Planet Source Code	Sample Source Code
VBCode.com	Free Source Code for VB
A1VBcode.com	Another Free Source Code site for VB
VBexemple.com	Free examples(source code), Tutorials for Visual Basic 6.0

Authors and Contributors

Details of permissions given to include content from other sites and documents is on the Credits and Permissions page.

Name	Comment
Batjew	Wrote almost everything to start, getting help now.
EugeneH	Corrected mistakes and wrote the rest. User name is now Orage
T94xr	Fixed a dead link and added a couple good sites.
kwhitefoot	Added: distinction between Type and Class, optimization of programs. Split into separate chapters. Added coding standards, case studies, optimization.
Elliot Spencer	Contributed many examples from his web site: http://www.ilook.fsnet.co.uk/index.htm
Aadnk	Some sections translated from the Norwegian Visual Basic WikiBook (by Kwhitefoot). Also wrote the Windows Dialogs chapter.
GUI Computing Pty Ltd/Mark Trescowthick	Mark Trescowthick kindly gave permission for the [GUI Computing coding standards] and [Australian Visual Developers Forum] to be used, see Credits and Permissions.