Introduction to Visual Basic Programming

Lecture Outline

• History• What is Visual Basic• First Look at the VB 6.0 Environment• Some VB Terminology• Our first VB Program

History

BASIC• BASIC (Beginner's All-purpose Symbolic Instruction

Code) • Designed in 1964, by Kemeny and Kurtz at Dartmouth • Goal was to provide access for non-science students to

computers. • Back then all use of computers required writing

custom software– But only Computer Scientists/Mathematicians did this

• Language became widespread on microcomputers in the late 1970s and home computers in the 1980s.

A Simple BASIC Program

MS DOS Command Line

MS-DOS Shell

Visual Programming (MS Windows 3.1)

Visual Programming Today (MS Vista)

What is Visual Basic?

What is Visual Basic?

Visual Basic (VB) is a Microsoft Windows programming language (SOFTWARE development language)

Visual Basic is derived from the BASIC (Beginners All-purpose Symbolic Instruction Code) programming language

BASIC was developed in the mid-1960sThe widespread use of BASIC led to many enhancements to

the languageIn the late 1980s and early 1990s, with the development of the Microsoft Windows (Graphic User Interface) GUI, the natural evolution of BASIC was Visual Basic (created by

Microsoft in 1991)

VB greatly simplifies the development of Microsoft Windows-based Applications

Between 1991 and 1998 6 versions of VB were released, with Visual Basic 6 appearing in September 1998.

Microsoft provides several versions of VB, namely the Learning Edition, the Professional Edition and the Enterprise Edition

VB programs are created in an Integrated Development Environment (IDE). The IDE allows a programmer to create,

run and debug VB programs conveniently.

The process of rapidly creating an application is typically referred to as Rapid Application Development (RAD). VB is the

most widely used RAD language.

The Visual Basic Environment

Visual Studio

The Visual Basic Environment

In using VB you will learn to write computer programs that run in the Microsoft Windows environment

Projects will look and act like standard Windows programs

VB provides the tools you need to create windows with familiar elements like: Menus, Text Boxes, Command Buttons, Option Buttons, Check Boxes, List Boxes, and

Scroll Bars

Microsoft Windows uses a Graphic User Interface (GUI)

The Windows GUI defines how the various elements look and function

Within VB there is a Toolbox of these elements

In VB you will create new Windows called Forms

Using the toolbox to add the various elements, called Controls, to the form

VB programming is known as Event-Driven Programming

The Initial Visual Basic Screen

Toolbox

Project Explorerwindow

Properties window

Form

Menu bar

Description pane

Form Layout window

Toolbar

Project Container window

Some VB Terminology

Objects, Properties and Methods

In VB you work with Objects, which have Properties and Methods

Objects: Think of an Object as a thing, or a noun

Examples of Objects are Forms and Controls

Forms are the Windows and Dialog Boxes that you place on the screen

Controls are the elements you place inside a form, such as Text Boxes, Command Buttons, and List Boxes

Properties: Think of Properties as adjectives that describe objects

Properties tell something about an Object, such as the name, colour, size, location, and how it will behave

When you refer to a Property[1] Name the Object [2] Name the Property

(Example: Form1.Caption)The Caption Property of the Object (Form) called Form1

Methods: Methods are the verbs of Object-Oriented Programming

Methods are Actions associated with Objects

Example of Methods include Move, Print, Resize, and Clear

Refer to Methods as:Object.Method

(Example: Form1.Print)Sends output (Prints) to the Object (Form) called Form1

(Question: What does this Method refer to?)Printer.Print

Steps to Create a Visual Basic Program

1. Create the interface by placing controls on the form

2. Set properties for the controls and the form3. Write code for event procedures associated

with the controls and the form

Placing a Text Box on a Form

• Double-click on the text box icon in the toolbox to add a text box to your form

• Activate the properties window (Press F4)• Set values of properties for text box

Placing a Text Box on a Form

Text box

Our First VB Program

“Hello World”

Private Sub cmdPush_Click

‘Display the ‘Hello World’ Message

lblMessage.Caption = “Hello World”

End Sub***********************************************Private Sub cmdExit_Click

‘Exit the project

End

End Sub

Comment

Assignment

Naming Objects:Object Prefix Example

Command Button cmd cmdStart

Form frm frmPayroll

Label lbl lblName

Picture box pic picClouds

Text box txt txtAddress

Visual Basic Events

• Code is a set of statements that instruct the computer to carry out a task.

• Code can be associated with events • When an event occurs, the code associated

with that event (called an Event Procedure) is executed.

Creating An Event Procedure• Double-click on an object to open a Code

window. (The empty default event procedure will appear. Click on the Procedure box if you want to display a different event procedure.)

• Write the code for that event procedure.

Example of An Event Procedure

Private Sub objectName_event ( ) statementsEnd Sub

Private Sub txtOne_GotFocus( ) txtOne.Font.Size = 12 txtOne.Font.Bold = FalseEnd Sub

More Examples

Private Sub cmdButton_Click( ) txtBox.ForeColor = vbRed txtBox.Font.Size = 24 txtBox.Text = “Hello”End Sub