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VISUAL BASIC®

Introduction to

Visual Basic®

Copyright © 2014 Dan McElroy

Table of Contents

1. What is Visual Basic

2. Visual Basic Controls

3. Developer and Run Modes

4. View Designer, View Code

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What is Visual Basic®

Visual Basic (VB) is a programming

language provided as part of Microsoft

Visual Studio for developing application

programs for Microsoft Windows®

Although VB is most often used for

developing Windows applications, it can

also be used for non-Windows projects.

1) What is Visual Basic

Visual Basic Uses Objects

Visual Basic (VB) is an object-based language which gives the programmer to opportunity to do Object Oriented Programming (OOP). Other object-based languages include: C++, Objective-C, Swift, Smalltalk, Java, C#, Perl, Python, Ruby and PHP.

VB provides a collection of objects in its Toolbox that can be placed on a Form. Objects in the Toolbox are called controls. The VB Form provides the layout of what the VB program will look like when it is completed and is run by the user.

Controls 1/3

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Visual Basic Controls

This sample program includes the following controls that were selected by the programmer from the Toolbox.

Controls 2/3

Label (Text)

Button

TextBox (User Input)

NOTE: The Form is also an object.

Controls – Properties and Methods Each of the controls from VB’s Toolbox already have Properties (data, attributes) and Methods (code, functions, subroutines, procedures) that will do things to the control or respond to Events that happen to the control.

Most controls include:

Controls 3/3

Properties Methods

Font Click

Font Color Move

Location MouseDown

Size Resize

Text TextChanged

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Visual Basic Modes

Visual Basic has two modes of operation:

a) Developer Mode – The VB program is created by designing the Form (what the program looks like when it runs in Windows) and the code to make the program work.

b) Run Mode – Debug, execute and test the program with known values to make sure it works properly. Publish the program for other users to run the program.

Modes

1)

Developer Mode Two parts of the Developer Mode

1) The Design Window - The programmer places controls from the Toolbox on the Form that will be displayed when the program runs.

2) The Code Window – The programmer writes the code that will be executed when the program runs.

Modes – Developer Mode

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The Design Window When developing the program, select an control from the Toolbox then use the mouse to draw a rectangular area on the Form to select its size and position.

Modes – Developer Mode – The Design Window 1/4

The Design Window The most common controls used from the Toolbox include:

Label – Used to place text on the form or used to display the results to the user

TextBox – Get input from the user of the program

Button – Make something happen in the program PictureBox – put a picture on the Form

Modes – Developer Mode – The Design Window 2/4

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The Design Window

Modes – Developer Mode – The Design Window 3/4

Label

TextBox

Button

Label1.Text

Properties Label1.Location

Label1.Size

Controls are selected from the Toolbox and placed on the form. Each control has a list of properties that can be displayed or modified in the Properties window.

Button

Label

The Properties Window The Properties Window can display either Properties or Event Handlers

Modes – Developer Mode – The Design Window 4/4

The Properties or Event Handlers can either be displayed by Category or Alphabetically. The Alphabetic display is used for all the discussions and videos.

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The Code Window The Code Window is the place where the programmer can type the program. The program can consist of:

1) Event Handlers – code that gets executed when something happens to a control, such as a button being clicked.

2) Subroutines and Procedures – extra code created by the programmer to help the program run.

Modes – Developer Mode – The Code Window 1/4

The Code Window

While in the Design Window, double-clicking a control opens the Code Window with an empty Event Handler subroutine.

Modes – Developer Mode – The Code Window 2/4

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The Code Window The programmer can enter the code that is to be executed during the Run Mode.

For example, the first Event Handler subroutine in the example below shows what code is to be executed when the “Compute” button is clicked.

Modes – Developer Mode – The Code Window 3/4

The Code Window When entering code, BE VERY CAREFUL that you only enter the program between the Private Sub and the End Sub lines provided by Visual Basic.

If you modify or delete any of the lines provided by VB, you may need to start your project all over from the beginning.

Modes – Developer Mode – The Code Window 4/4

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Switching Views

You can easily switch between the Design Window and the Code Window by clicking the tabs at the top of the window. The View menu selection can also be used.

Modes – Developer Mode – Switching Views

Divide and Conquer Medium or large sized programs are usually divided into smaller pieces called; methods, functions or subroutines. Example: A very simple payroll program. The work is subdivided so that each part of the program does only one thing – and does it well.

Modes – Developer Mode – Switching Views

main FormLoad

Read Hours

Compute Pay

Compute Taxes

Print Paycheck

Hours Hours Pay Pay Taxes Net pay

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Event Handlers Event handlers are a special form of a subroutine that are activated by an event occurring on a control instead of being called (activated) by the main program. Examples might be a Button is clicked, text is changed in a TextBox, a tick occurred on a timer, etc.

Modes – Developer Mode – Switching Views

main FormLoad

Read Hours

Compute Pay

Compute Taxes

Print Paycheck

Hours Hours Pay Pay Taxes Net pay

Button

Review Paycheck

Click Event

Review

Have Fun With Programming

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ACKNOWLEDGEMENTS

IMAGE

DMV image – UCSF

VISUAL BASIC and MICROSOFT WINDOWS

are registered trademarks of Microsoft Corp.