CVEV 118/698CVEV 118/698 Visual Basic Visual Basic

Lecture 1Lecture 1

Prof. Mounir MabsoutProf. Mounir MabsoutExpert 1: Elsa SulukdjianExpert 1: Elsa SulukdjianExpert 2: Walid El AsmarExpert 2: Walid El Asmar

IntroductionIntroduction

Visual Studio 6.0: Collection of Microsoft Visual Studio 6.0: Collection of Microsoft Visual development applications (Visual Visual development applications (Visual C++, Visual J++, Visual Basic, etc…)C++, Visual J++, Visual Basic, etc…)

VB is a programming language. 6 VB is a programming language. 6 Versions launched since its creation in Versions launched since its creation in the 90’s.the 90’s.

““Easy and powerful tool for developing Easy and powerful tool for developing Windows applications in Basic.” Bill Windows applications in Basic.” Bill Gates.Gates.

VB Development VB Development EnvironmentEnvironment

Integrated Development Environment (IDE): Integrated Development Environment (IDE): vvisual environment to develop, run, test and isual environment to develop, run, test and debug.debug.

Controls: Controls: generally visual, and readymade generally visual, and readymade components, assigned a set of properties (I.e. components, assigned a set of properties (I.e. Text Box, Button, List Box, etc…). Text Box, Button, List Box, etc…).

IntelliSense: IntelliSense: Microsoft’s sophisticated Microsoft’s sophisticated completion technology. It simplifies the coding completion technology. It simplifies the coding process.process.

Event driven programming:Event driven programming: f flow of the low of the application dictated by the user actions (click application dictated by the user actions (click of a mouse, keystrokes, etc…).of a mouse, keystrokes, etc…).

VB IDEVB IDEmenu bar

Toolbar

Project Explorer

Properties window

Form layout

Toolbox

Immediate window

VB IDE ComponentsVB IDE Components Menu Bar:Menu Bar: contains all commands needed to contains all commands needed to

run VB (File, Edit, View etc…).run VB (File, Edit, View etc…). Toolbars:Toolbars: quick access to commonly used quick access to commonly used

menu commands.menu commands. Project Explorer:Project Explorer: displays the project’s displays the project’s

components.components. Toolbox: Toolbox: contains icons of the controls that contains icons of the controls that

can be placed on the project’s Forms to create can be placed on the project’s Forms to create the application’s interface.the application’s interface.

Properties Window: Properties Window: Shows the property Shows the property settings of the selected control (size, caption, settings of the selected control (size, caption, color, etc…).color, etc…).

VB IDE Components VB IDE Components (Cont’d)(Cont’d)

Form Designer:Form Designer: Main window in which Main window in which one can design and edit the application’s one can design and edit the application’s user interface. In this window the user user interface. In this window the user can enter and edit the application’s code. can enter and edit the application’s code. It displays two windows: Form and Code It displays two windows: Form and Code window.window.

Form Layout:Form Layout: Shows the initial positions Shows the initial positions of the forms in the application. It is of the forms in the application. It is useful in multiple forms applications.useful in multiple forms applications.

Immediate Window:Immediate Window: Debugging tool. Debugging tool.

Programming StepsProgramming Steps

Step 1: Step 1: Customize the windows that Customize the windows that the user sees. I.e. placing controls the user sees. I.e. placing controls and components on the layouts of and components on the layouts of the project’s Forms.the project’s Forms.

Step 2: Step 2: Decide on the events each Decide on the events each control should recognize.control should recognize.

Step 3:Step 3: Coding the event Coding the event procedures for those events. procedures for those events.

Variable DeclarationVariable Declaration

Visual Basic code works in two Visual Basic code works in two modes:modes:– Implicit:Implicit: does not require variable does not require variable

declarationdeclaration– Explicit:Explicit: requires variable declaration requires variable declaration

Declare variables usingDeclare variables usingDim Dim VariableNameVariableName As As DataTypeDataType

Example:Example: Dim length As IntegerDim length As Integer

Dim greetings As StringDim greetings As String

Variable TypesVariable Types

Numeric: Numeric: stores numbers String: stores text Variant: stores any type of data Boolean: true/false Date Object

Implicit/ExplicitImplicit/Explicit Implicit ExampleImplicit Example Public Sub VBImplicit()

x = 5y = “Hello”

End Sub

Explicit ExampleExplicit ExampleStart code window by: Option Explicit […] Public Sub VBExplicit() Dim x As Integer, y As

String x = 5 y = “Hello”

End Sub Implicit: Implicit: default VB mode, x and y stored default VB mode, x and y stored

as variantsas variants Explicit: Explicit: x can only store integers, y only x can only store integers, y only

stringsstrings ALWAYS use explicit mode, it reduces ALWAYS use explicit mode, it reduces

errorserrors

Variable ScopeVariable Scope

Sub1Sub1 Variables

Form 1

Sub2Sub2 Variables

...

Form1 Variables

Code

Form 2

Code

Variable Scope (cont’d)Variable Scope (cont’d)

Dim x As Integer

Public Sub FirstSub()x = 5 Dim y As Integer

End Sub

Public Sub SecondSub()

x = 6Dim y As String

End Sub

The The samesame variable variable x x is needed in both is needed in both subroutines and subroutines and therefore is defined therefore is defined as a as a global variable global variable (I.e. declaration (I.e. declaration outside subs)outside subs)

There is a different There is a different locallocal variable variable yy for for each subroutine (I.e. each subroutine (I.e. declaration inside declaration inside subs)subs)

Variable GeneralitiesVariable Generalities Variable names need to be significant for

clear coding practice. Don’t be shy of using long names. Usually the first character(s) indicate the

variable type (e.g):– Integer: int… Dim intLength As

Integer– String: str…– Double: dbl…– Text Control: txt– Etc.

ConstantsConstants

Constants do not change their value during the execution of the program.

Declaration: Const ConstantName As DataTypePublic Const pi As Double =

3.14159265358979

ArraysArrays

Arrays hold a set of related data. Declaration:

Dim ArrayName(ArraySize) As DataTypeDim strNames(15) As String

or Dim strNames(1 To 16) As String

strNames is an array that holds 16 string values.

Multidimensional arrays:Dim dblTemperature(99,99) As Double

Dynamic ArraysDynamic Arrays

Size not defined at the beginning of the program:Dim dblMatrix() as Double

You can re-dimension the array once you know the size of the array:ReDim dblMatrix(UserCount,UserCount)

What’s NextWhat’s Next

Basic VB syntaxBasic VB syntax Functions and SubroutinesFunctions and Subroutines Common VB controlsCommon VB controls