CC111 Lec7 : Visual Basic 1

Visual Basic(1)

Lecture 7

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Objectives

• The student should be familiar with the Visual Basic Environment.

• The student should be able to build a simple Visual Basic Application.

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What is Visual Basic?

• High Level 4th Generation Programming Language

• Object and Event Driven

• Visual - Windows Based

• Integrated Development Environment or IDE

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What is VB Used For?

• Most Popular Programming Language• Stand alone programs• Customized specialized Applications

– E- Commerce • Web based shopping forms and inquiries

• User friendly Interface to applications

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Used by a computer equipment retail outlet to record data regarding customer

orders.

Example Order Entry Screen

Allows user to use a mouse to click on boxes for text entry.Also enables user to click on buttons

to initiate processing steps.

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Generations of Computer Languages

• 1st - Machine language - 0110 0011 1000• 2nd - Procedure-oriented languages

– FORTRAN - 1954 for scientists and engineers

– COBOL - 1959 for business applications

– C - 1972 - for UNIX operating systems

• 3rd - Object-oriented languages• 4th - Event-driven languages. Example:VB• 5th - Natural languages

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Compiler Vs Interpreter

• Higher Languages are translated to Machine Language by:

– Interpreter

• Translates instructions to machine code line-by-line.• BASIC, Quick Basic, Visual Basic

– Compiler

• Translates the entire program to machine code before running it.

• Fortran, C, C++, Visual Basic is also a compiler

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What are the Objects in VB?

• Pre-programmed Code for:– Command Buttons– Labels– Pictures– Text Boxes

• Have both data and procedures wrapped together

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What is the Integrated Development Environment (IDE)?

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Visual Basic Environment

GUI (Graphical User Interface) - forms and windows that the user sees

Property - a characteristic or attribute of an object such as color and size

Event - a user action such as clicking a buttonCode Editor window - editor specially designed to help

you when writing code

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The Form Designer Window show the GUI application The Toolbox is used to drag and drop components to your

forms The Properties window show the value od of the properties of

each selected component(Object)

Visual Studio 2008 IDE Environment

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Visual Basic Environment

• Components of the VB design environment (Form view)

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Visual Basic Environment

• Components of the VB design environment (Code view)

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The Code Editor Window

Help window

Error message box

Syntax error in Red

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Properties Window

• Used to set how a control looks and behaves

• Holds its default values

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Control Toolbox

Pointer

Label

Group Frame

Check Box

Combo Box

Horizontal Scroll Bar

Timer

Directory List Box

Shape

Image

OLE

Picture

Text Box

Command Button

Option/Radio Button

List Box

Vertical Scroll Bar

Drive List Box

File List Box

Line

Data Control

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Building Your First Application

• There are three primary steps in building a Visual Project:

1. Place (or draw) controls on the form.

2. Assign properties to the controls.

3. Write event procedures for the controls.

WelcomeApplication.exe

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Starting Visual Basic

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Starting Visual Studio 2008

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Creating New Project

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Project initial interface

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Step1 :Draw your controls

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Step 2 : Assign Properties

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Changing the Form Title

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Changing the Form Title……………

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Edit Image Properties

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Browse for an Image

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Edit the SizeMode property of the PictureBox

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Edit the Text Property of Label1

The Text Property is changed to “ “

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Accessing components properties from code

Label1

PictureBox1

Button1

Each Component has a name, you access its property by: componentName.PropertyName

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Step 3:Writing the Code (Events)

Double click on the Button then write your code

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Writing the Code (Events)

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Running the Application