Computer Programming - Visual Basic

8/8/2019 Computer Programming - Visual Basic

http://slidepdf.com/reader/full/computer-programming-visual-basic 1/39

Computer StudiesChapter 1

Introduction to the Visual BasicLanguage and Environment



W hat is Visual Basic?

a tool that allows you to developWindows (Graphic User Interface - GU I)

applications.It is event-driven, meaning code remainsidle until called upon to respond to some

event (button pressing, menu selection, ...).It is governed by an event processor.



Event Processor

Once an event is detected, the codecorresponding to that event (event procedure)is executed. Program control is then returnedto the event processor.



Some Features of Visual Basic

Sequential and random access file supportUseful debugger and error-handling facilities

Powerful database access toolsActiveX supportPackage & Deployment Wizard makes

distributing your applications simple



Visual Basic 6.0 versus Other Versionsof Visual Basic

The original Visual Basic for DOS and VisualBasic For Windows were introduced in 1991.

Visual Basic 3.0 - 1993.Visual Basic 4.0 - 1995 (added 32 bitapplication support).

Visual Basic 5.0 - 1996. New environment,supported creation of ActiveX controls,deleted 16 bit application support.



S tructure of a Visual Basic Application



Application (Project) is made up of:

Methods - Built-in procedure that can be invokedto impart some action to a particular object.Event Procedures - Code related to some object.This is the code that is executed when a certainevent occurs.G eneral Procedures - Code not related to objects.This code must be invoked by the application.Modules - Collection of general procedures,variable declarations, and constant definitionsused by application.



S teps in Developing Application

1. Draw the user interface2. Assign properties to controls

3. Attach code to controls



Drawing the U ser Interface andS etting Properties

Visual Basic operates in three modes. ± Design mode - used to build application ± R

un mode - used to run the application ± Break mode - application halted and debugger is

available



Main W indow



Form W indow

Is central to developing Visual Basicapplications. It is where you draw yourapplication.



Toolbox

Is theselectionmenu forcontrols usedin yourapplication.



Properties W indow

is used toestablishinitialpropertyvalues forobjects.



Form Layout W indow

shows where (uponprogram execution)your form will bedisplayed relative toyour monitor sscreen:



Project W indow

displays a list of all forms andmodulesmaking up yourapplication.



Exercise 1Hello World!

Create a simple program that will displayHello World! using Visual Basic



Exercise 2S topwatch Application - Drawing

Controls



A Brief History of BasicLanguage developed in early 1960's atDartmouth College

± B (eginner's) ± A (All-Purpose) ± S (Symbolic) ± I (Instruction) ±

C (Code)Answer to complicated programming languages(FORTRAN, Algol, Cobol ...).First timesharelanguage.



A Brief History of Basic

In the mid-1970's, two college students writefirst Basic for a microcomputer (Altair) - cost$350 on cassette tape. You may have heard of them: Bill Gates and Paul Allen!Every Basic since then essentially based onthat early version. Examples include: GW-Basic, QBasic, QuickBasic.Visual Basic was introduced in 1991.



Visual Basic S tatements and

ExpressionsThe simplest statement is the assignmentstatement. It consists of a variable name,followed by the assignment operator (=),followed by some sort of expression.Examples:

± Start T ime = Now ± Explorer.Caption = "Captain Spaulding" ± BitCount = ByteCount * 8 ± Energy = Mass * LIGH TSPEE D ^ 2 ± NetWorth = Assets - Liabilities



Comment statements

begin with the keyword R em or a single quote(')Example

Rem T his is a remark' T his is also a remarkx = 2 * y ' another way to write a remark or comment



Visual Basic Operators

Operator Operation^ Exponentiation

* / Multiplication and division\ Integer division (truncates)Mod Modulus

+ - Addition and subtractionParentheses around expressions can change

precedence.



Comparison operatorsOperator Comparison> Greater than< Less than> = Greater than or equal to<= Less than or equal to= Equal to<> Not equal toThe result of a comparison operation is a

Boolean value ( True or False).



Logical operators

Operator OperationNot Logical not

And Logical andOr Logical orT he Not operator simply negates an operand.T

he And operator returns aTrue if both operands areTrue. E lse, it returns a False.

T he Or operator returns a True if either of its operandsis True, else it returns a False.



Common Visual Basic Functions

Format Date or number converted to atext string

Now Current time and dateSqr Square root of a numberStr Number converted to a text

stringT ime Current time as a text stringVal Numeric value of a given text

string



E xercise 3S avings Account



Visual Basic Branching

Branching statements are used to cause certainactions within a program if a certain conditionis met.

The if statement is used to check a conditionand if the condition is true, we run a block of statements (called the if-block ), else weprocess another block of statements (calledthe else-block ). The else clause is optional.



If S tatements

The simplest is the If/ Then statement:If Balance - Check < 0 Then

Print "You are overdrawn³Here, if and only if Balance - Check is less thanzero, the statement You are overdrawn isprinted.



If S tatements

You can also have If/ Then/End If blocks toallow multiple statements:

If Balance - Check < 0T

henPrint "You are overdrawn"Print "Authorities have been notified"

End If In this case, if Balance - Check is less thanzero, two lines of information are printed.



If S tatementsIf/ Then/Else/End If blocks:If Balance - Check < 0 Then

Print "You are overdrawn"

Print "Authorities have been notified"E lse

Balance = Balance - CheckEnd If

Here, the same two lines are printed if you are overdrawn (Balance -Check < 0),but, if you are not overdrawn ( Else), your new Balance is computed.



If S tatementsOr, we can add the ElseIf statement:If Balance - Check < 0 Then

Print "You are overdrawn"

Print "Authorities have been notified"E lseIf Balance - Check = 0 Then

Print "Whew! You barely made it"

Balance = 0E lse

Balance = Balance - Check

End If



S elect Case - Another W ay toBranch

S elect Case format can be used when thereare multiple selection possibilities.

Runs one of several groups of statements,depending on the value of an expression.Select [ Case ] testexpression

[ Case expressionlist [ statements ] ][ Case E lse [ elsestatements ] ]

End Select



using the If statement:If Age = 5 T henCategory = "Five Year Old"

E lseIf Age > = 13 and Age <= 19 T henCategory = " Teenager"

E lseIf (Age > = 20 and Age <= 35) Or Age = 50 Or (Age > =60 and Age <= 65)

T henCategory = "Special Adult"

E lseIf Age > 65 T henCategory = "Senior Citizen"

E lseCategory = " Everyone E lse"

E nd If



code with S elect CaseSelect Case AgeCase 5

Category = "Five Year Old"Case 13 To 19

Category = " Teenager"

Case 20 To 35, 50, 60 To 65Category = "Special Adult"

Case Is > 65

Category = "Senior Citizen"Case E lse

Category = " Everyone E lse"E

nd Select



E xercise 4Password validation

Computer Programming - Visual Basic

Documents

Transcript of Computer Programming - Visual Basic

O'reilly programming visual basic .net

Introduction to Visual Basic Programming Chapter 3 – Introduction to Visual Basic Programming.

Introduction to Visual Basic Programming Introduction to Visual Basic Programming Ch3 – Deitel’s Book.

VISUAL BASIC PROGRAMMING-18BIT43C

Visual basic programming session 3

Programming visual basic .net

Mastering Visual Basic .Net Database Programming

Introduction to Programming Fundamentals of Programming in Visual Basic.

VISUAL PROGRAMMING 2 - bangdanu.files.wordpress.com fileWhat’s Visual Basic.NET •Visual Basic .NET was an object oriented programming which was the latest version from Visual BASIC

Programming Guide with Visual Basic

Microsoft Visual Basic 6 (Basic Programming Fundamental)

Visual Basic for Applications - Programming Excel

and Programming - Cengagecengage.com.cn/data/upfiles/catalog/Acad Asia Computer Science n... · and Programming and Programming. ... Visual Basic Clearly Visual Basic ... • Provides

Visual basic asp.net programming introduction

IS660Z Programming Games Using Visual Basic

Visual Basic Programming Using Excel

Programming visual basic

GIS and Programming with Visual Basic - University of ... and Programming with... · GIS and Programming with Visual Basic Example: Trend Surface ... Visual Basic: Assignment Statements

Clearly Visual Basic: Programming with Visual Basic 2008

VISUAL BASIC 6 - webzdarmavbhelp.wz.cz/stahuj/PCAVB.pdf · Computer Programming Concepts and Visual Basic ... An Introduction to Programming Using Visual Basic 6.0, ... program is