PROBLEM SOLVING

The first step in writing instructions to carry out a task is to determine what the output should be (What should

the task produce?)

The second step is to identify the data, or input, necessary to obtain the output

The final step is to determine how to process the input to obtain the desired output

INPUT OUTPUTPROCESSING

PROGRAM DESIGN TOOLS

Flowcharts: graphically depict the logical steps to carry out a task and show how the steps relate to each other

Pseudocode: uses English-Like phrases with some (Visual Basic) terms to outline the task

Hierarchy Charts: show how the different parts of the program relate to each other (referred to as Structure Charts, HIPO (Hierarchy plus Input-Process-Output) Charts, Top-Down Charts or VTOC (Visual Table of

Contents) Charts.)

RENTING A VIDEO

START

GET CUSTOMER NUMBER

REFUSE RENTAL PROCESS

RENTAL PROCESS

GET VIDEO NUMBER

VALIDATE NUMBER

PROCESS CUSTOMER

NUMBER

END

VALIDATE NUMBER

Valid

Invalid

InvalidValid

Achieve program clarity throughStructured Programming

Event-Driven ProgrammingObject-Oriented Programming

Newer Methodologies

Event-Driven Programming - work with Events

Object-Oriented Programming - work with Objects

The internal structure of Objects and Events is best built using Structured Programming Techniques

Also, the logic of manipulating objects is occasionally best expressed with Structured Programming

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

Since 1991, 6 versions of VB have been released, with the latest 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

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

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

There is a ‘Three-Step’ process in Planning and Programming a VB project

Planning[1] Design the User-Interface

[2] Plan the Properties[3] Plan the VB ‘Basic’ Code (in the planning stage

this is referred to Pseudocode)

Programming[1] Define the User-Interface

[2] Set the Properties[3] Write the VB ‘Basic’ Code

Visual Basic Project Files:

.VBP file: Project File: a small text file that contains the names of other files in the project, as well as

some information about the VB environment(release 2.0 and 3.0 of VB, .MAK extensions for

project files)

.FRM file: Form File: each form in the project is saved in a .FRM extension. Each form file holds a

description of all Objects and their Properties for the form, as well as the Basic Code written

(In VB each of these Form Files is referred to as a Form Module)

.BAS file: Standard Code Modules: hold VB ‘Basic’ statements that can be accessed from any Form

.BAS files are used in multiform projects

.OCX file: Custom Controls: additional controls/custom controls are stored in .OCX files. If

projects include controls that are not part of the Standard Control Set, then .OCX file names will be

included in the project(All controls have .OCX extensions, however, this is implicit in controls internal to the VB Environment,

and these extensions are not visible to the user)

.VBW file: after the project is saved, VB automatically adds one more file to the project, which holds

information about each of the project Forms

Project TipCreate a New Folder for a project, before creating any

files for the projectSave the .VBP file

Save the .FRM files, and Save the .BAS files into the folder

Then if the project needs to be copied or transferred from the ‘C: Drive’ to the ‘A: Drive’, all of the project

files can be transferred together within the folder, and no component parts (.VBP, .FRM, .OCX[if existing])of

the project will be lost

Component parts of a project can be lost and always save each component part separately

The VB Environment

VB Environment, where projects are created

The various windows, in the VB Environment, can be moved, resized, opened, and closed

The windows within a project can be customised

FORM

TOOLBOX

FORM WINDOW

TOOLBARMENU BAR

PROJECT EXPLORER WINDOW

FORM LOCATION & SIZE INFORMATION

PROPERTIES WINDOW

PROPERTIES HELP PANE

FORM LAYOUT WINDOW

FORM1: NAME OF THE OBJECT

FORM: CLASS OF THE OBJECT

POINTER (NOT A CONTROL)

LABEL

FRAME

DRIVELISTBOX

FILELISTBOX

LINE

DATACONTROL

CHECKBOX

COMBOBOX

HSCROLLBAR

TIMER

DIRLISTBOX

SHAPE

IMAGE

OLE

PICTUREBOX

TEXTBOX

COMMANDBUTTON

OPTIONBUTTON

LISTBOX

VSCROLLBAR

The Form Window is where the forms are designed that make up the User-Interface

Always create a ‘User-Friendly’ User-Interface

Standard windows techniques can be used to change the size and location of the form

‘Mouse-Driven Environment’

By default, a new form created in a new project, is called Form1, when the file is saved, the programmer

assigns a more meaningful name to the file(?: What is the extension?)

The Project Explorer Window holds the filenames of the files included in the project

The windows Title Bar holds the name of the project, which is Project1 by default, until saved and given a

more meaningful name (?: What is the extension?)

The Properties Window, its use relates to setting the properties for the objects in the project

Check Box 1/0, True/FalseOption Box 1/0, True/False

Command Button ‘Name’ how the computer recognises/identifies the control/object

‘Caption’ relates to the user identification of the control/object

Text Box ‘Text’ property: ‘Blank’‘Name’ property: like command button

Form Window State ‘Maximise’, relates to maximising the form when the project is executed

The Form Layout Window, this indicates the position of the form on the desktop, when the execution of the

project begins

The Toolbox holds the tools that are used to place controls on the form

The tools displayed on the toolbox, may be different, depending on the edition and release of VB being

used

‘Professional Edition’

The Main Visual Basic Window holds the VB menu bar, the toolbar, and the form location and size

information

The Toolbar, the buttons on the toolbar can be used as shortcuts for frequently used operations

Each button represents a command that can be executed by clicking on the button or by choosing a

command from the menu bar

The Form Location and Size Information identifies the size and position of the form on the screen

Help VB has an extensive ‘Help’ facility

VB contains what is called ‘Context-Sensitive’ help

Design Time, Run Time, Break Time

VB has 3 distinct modes:

Design Time: relates to designing the ‘User-Interface’ and writing code

Run Time: relates to testing and running the project

Break Time: if there is a ‘run-time error’ or project execution is paused

VB Project Example

The first ‘Event-Driven’ project will create a form with 3 controls

It will display the message ‘Hello world’ when the user clicks the ‘Push Me’ command button, and will terminate when the user clicks the ‘Exit’ command button

(Tip: If the Project Explorer Window/Properties Window/Toolbox are not displayed, open the View menu and select Project Explorer Window/Properties Window/ Toolbox

Project Tips

Do not confuse the ‘Name’ and ‘Caption’ properties

‘Name’ refers to the control in the VB code‘Caption’ refers to the users view on the form

VB sets both of these properties to the same value by default, and therefore it is easy to confuse them

NB: Always set the ‘Name’ property of controls before writing code

If the ‘Name’ of an object is changed after the code has been written, then the code becomes separated from the

object and the program does not run properly

When a VB project is running, the user can do many things

Each action by the user causes an ‘Event’ to occur in the VB project

If you write VB code for a particular event, the VB will respond to the event and automatically execute your

procedure (eg: clicking on a command button)

VB ignores events for which no procedures are written

(eg: moving the mouseresizing a window

opening another application)

VB code written in proceduresWe deal with writing code in ‘Sub Procedures’ or ‘Sub

Programs’

Begins with: Private SubEnds with: End Sub

VB automatically names the event proceudres

The ‘Name’ consists of the object name, an underscore ( _ ), and the name of the event

(name of the command button is cmdPush and there is a Click event for the command button

Therefore, the name of the Sub Procedure:

cmdPush_Click

VB Code Statements

3 types of VB statement

The Remark statement, known as comments, are used for project documentation only Begin with an

apostropheNot executable

Comments make the project more readable and understandable

The inclusion of comments is seen as good programming practice

It is a good idea to comment within the logic of the project, especially if the purpose of any statement is

unclear

The Assignment statement assigns a value to a property or variable

Assignment statements operate form Right to Left, that is the value appearing on the right hand side of the equal sign (=) is assigned to the property named

on the left of the equal sign

(Example: lblTitle.FontSize = 12Let lblTitle.FontSize = 12)

The use of ‘Let’ is optional, and its use may improve the readability of the project code

When the value to assign is ‘actual text’, known as a Literal, it is enclosed in quotation marks

This allows any combination of alpha and numeric characters to be typed

However, if the value is numeric, (eg: 12), do not enclose it in quotation marks

Do not place quotation marks around the term True or False, as VB recognises these as Special Key

Terms (Blue in colour, within VB code)

The End statement stops the execution of the project

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