week08_vb_final.pdf

8/14/2019 week08_VB_final.pdf

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CC111INTRODUCTION TOCOMPUTERS

VISUAL BASIC

Computer Engineering DepartmentAdopted from AAST Alex Branch


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Intended Learning Objectives

Familiar with the Generation of computerLanguages.

High level of languages translationFamiliar with the Visual Basic Environment.Able to build a simple Visual BasicApplication.


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What is Visual Basic?

High Level4th Generation ProgrammingLanguage

Object and Event DrivenVisual - Windows Based

Integrated Development Environment ( IDE)


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What is VB Used For?

Most Popular Programming Language

Stand alone programs

Customized specialized ApplicationsE- Commerce

Web based shopping forms and inquiries

User friendly Interface to applications


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Used by a computer equipment retail outletto 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 initiateprocessing steps.


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Generations of Computer Languages

1st - Machine language - 0110 0011 10002nd - Procedure-oriented languages

FORTRAN -1954 for scientists and engineersCOBOL - 1959 for business applicationsC - 1972 - for UNIX operating systems

3rd - Object-oriented languages4th - Event-driven languages. Example: VB

5th - Natural languages


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Compiler Vs Interpreter

Higher Languages are translated toMachine Language by:

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

Compiler Translates the entire program to machine codebefore 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

LabelsPicturesText Boxes

Have both data and procedureswrapped together


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What is the Integrated DevelopmentEnvironment (IDE)?


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Visual Basic Environment

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

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

Event - a user action such as clicking abutton

Code Editor window - editor speciallydesigned to help you when writing code


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The Form Designer Window show the GUI applicationThe Toolbox is used to drag and drop components to your formsThe Properties window show the value od of the properties of each selectedcomponent(Object)

Visual Studio 2008 IDE Environment


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Components of the VB design environment (Form view)


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Components of the VB design environment (Code view)


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The Code Editor Window

Helpwindow

Error message box

Syntax error in Red


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Properties Window

Used to set how a control looksand 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 BoxLine

Data Control


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Building Your First Application

There are three primary steps in building a VisualProject:

Place (or draw) controls on the form.Assignproperties to the controls.Write event procedures for the controls.

WelcomeApplication.exe
http://localhost/var/www/apps/conversion/tmp/scratch_1/WelcomeApplication.exehttp://localhost/var/www/apps/conversion/tmp/scratch_1/WelcomeApplication.exe


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Starting Visual Basic

S i Vi l S di 2008


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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

Edit I P ti


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Edit Image Properties


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Browse for an Image


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e ze o e proper y o ePictureBox


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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


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The Sub Statement

WherePrivate is the default procedure typeSub indicates beginning of procedurecontrolname is name of associated control

_ (underscore) required separatoreventname is name of corresponding event

( ) set of parentheses is requiredEnd Sub indicates end of a procedure

Private Sub ControlName_eventName(ByVal sender As System.Object, ByVal e AsSystem.EventArgs) Handles ControlName.eventName`

End Sub

Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click

Const pi = 3.14Dim r As IntegerDim area As Doubler = Val(TextBox1.Text)area = pi * r * rLabel3.Text = Str(area)

End Sub

Example on the Sub Statement


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Declarations, Variables, and Constants

Variable - a uniquely named storage location thatcontains data that changes during programexecution

Constant - a uniquely named storage locations thatcontains data that does not change during program

execution


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Declarations, Variables, and ConstantsRules for Naming Variables

Must begin with an alphabetic characterCan not contain a period (.)or type-declarationcharacters such as

%, &, !, #, @ or $Must be unique with same scopeMust be no longer than 255 characters

Should not be a reserved word

salary sal ary x$ salary4


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Declaring Variables

Declaration statement non executable code that setsaside storage locations for future use

Local variables - declared within a procedure or functionGlobal variables - declared in the general section of the

application


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Declaring Variables.

Declare variables using the Dim statements

Dim statement - value of variable preservedonly until procedure ends

Dim variablename As datatype


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The Dim Statement

Dim variablename As datatype

WhereDim is requiredvariablename should be a descriptive nameAs is requireddatatype is one of the following types:

Boolean, Byte, Date, Integer, Long,

Single, Double, Currency, String, Object or Variant

Dim x As Integer


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Declaring Variables

Data Types Boolean - True or falseDate - From Jan 1, 100 to Dec 31, 9999Integer - Numbers without a decimal pointLong - Long integerSingle - Numbers with a decimal pointDouble - Long Single

Currency - Dollar amountsString - Character and alphanumeric dataObject - Any object reference such as Word documentVariant - default, can hold any data type


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Assigning Values to Variables

Variablename =

valueWhere

variablename is the descriptive name of the variable= is the assignment operatorvalue i the value the variable will contain

Examples:Number1 = 5FirstName = Steve Length = 17.8

Note: Order is important. Variable name always on the left, and value on theright.

Variables can be declared and initialized in the same line:Ex::Dim x As Integer=12


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Declaring Constants

Cons t constantname As datatype = value

WhereConst is required

constantname is the descriptive name of the constantAs is requireddatatype is the type of data the constant will contain= is the assignment operatorvalue is the value of the constant

Examples:

Const Pi As Single = 3.14159265358979Const MaxNumber As Integer = 100


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Functions

Function - unit of code that returns a valueBuilt-in Functions

Math.Sqrt - square rootRnd - random number generatorInt - returns integer portion of a numberVal - converts a string to a valueStr - converts a value to a string


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Application 1: Calculate the area of a circle

Inputs: radius of the circle rOutput: area of the circle

Process: Area= 2r

Application 1: Calculate the area of a


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Application 1: Calculate the area of acircle (Form View)

Circle_Area_Calculator.exe

http://localhost/var/www/apps/conversion/tmp/scratch_1/Circle_Area_Calculator/bin/Debug/Circle_Area_Calculator.exehttp://localhost/var/www/apps/conversion/tmp/scratch_1/Circle_Area_Calculator/bin/Debug/Circle_Area_Calculator.exe


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Application 1: Calculate the area of a circle(Code View)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)Handles Button1.Click

Const pi As Double= 3.14Dim r As IntegerDim area As Doubler = Val(TextBox1.Text)area = pi * r * rLabel3.Text = Str(area)

End Sub



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Application 1: Calculate the area of a circle(Run)


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Precedence Table

Operator

( )

^

*, /

+,-

If precedence of two following operators isequal, then the evaluation starts from left toright.


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Simple Examples of Equations

Equation in normal form:1. Y=3X

2. Y=X-10+3(X-Z)3. Y=

X

l Equation in VBform:

1. Y=3*X2. Y=X-10+3*(X-Z)3. Y= Math.Sqrt(X)


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Application 2: Convert from Fahrenheit Degree to Celsius

Original formula: Celsius=5/9 (Fahrenheit - 32)

Visual Basic formula: Celsius=5/9*(Fahrenheit-32)

Input: Fahrenheit

Output: Celsius

Process: Celsius=5/9*(Fahrenheit-32)

Application 2


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Application 2Convert from Fahrenheit Degree to Celsius (Form View)

Temprature_Convert.exe

Application 2
http://localhost/var/www/apps/conversion/tmp/scratch_1/Temprature_Convert/bin/Debug/Temprature_Convert.exehttp://localhost/var/www/apps/conversion/tmp/scratch_1/Temprature_Convert/bin/Debug/Temprature_Convert.exe


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Application 2Convert from Fahrenheit Degree to Celsius (Code View)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.ClickDim f As DoubleDim c As Doublef = Val(TextBox1.Text)c = 5 / 9 * (f - 32)

Label2.Text = "Celsius=" + Str(c)End Sub

The + operator is used to concatenate stringsNote:

Application 2


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Application 2Convert from Fahrenheit Degree to Celsius (Run)

Application 3


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Application 3The Wind Chill Application

Write a program that calculates the windchill temperature Inputs: Wind Speed and TemperatureOutputs: Wind Chill Temperature

Application 3
http://www.usatoday.com/weather/wchilform.htmhttp://www.usatoday.com/weather/wchilform.htmhttp://www.usatoday.com/weather/wchilform.htmhttp://www.usatoday.com/weather/wchilform.htm


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Application 3The Wind Chill Application

Original formulaWC = 0.0817(3.71(V **0.5) + 5.81 - 0.25V)(T - 91.4) +

91.4Visual Basic statementWC = 0.0817 * (3.71 * Sqr(V) + 5.81 -(0.25 * V)) * (T -

91.4) + 91.4

Output: Wind Chill (WC)Input 1 T: TemperatureInput 2 V: Wind Speed


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Adding Controls and Changing their Properties


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Writing the CodePrivate Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim V As IntegerDim T As IntegerDim WC As Doublev = Val(TextBox1.Text)T = Val(TextBox2.Text)WC = 0.0817 * (3.71 * Math.Sqrt(V) + 5.81 - (0.25 * V)) * (T - 91.4) + 91.4

TextBox3.Text = Str(WC)

End Sub


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Running the Application

Wind_Chill.exe
http://localhost/var/www/apps/conversion/tmp/scratch_1/Wind_Chill/bin/Debug/Wind_Chill.exehttp://localhost/var/www/apps/conversion/tmp/scratch_1/Wind_Chill/bin/Debug/Wind_Chill.exe

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