MELJUN CORTES Vb Net Lecture----> HANDOUTS for VB.Net 2010

7/27/2019 MELJUN CORTES Vb Net Lecture----> HANDOUTS for VB.Net 2010

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Introduction to VB.NET

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Agenda

Why VB.NET

What is new in VB.NET

Update to VB.NET?

VB.NET Language Essential

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Why VB.NET (from technicalstandpoint)

The world of applications is changing:The move to Web

The need for reusability, centralizationand scalabilityMTS, COM+, and Component Servicescannot be fully taken advantage of byVB.SOAP: features can be implementedmore completely with .NET.

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Why VB.NET (cont.)

To get the benefit of .NETframework and its core execution

engine: CLR.Garbage collection

OO mechanism

Standard security servicesIntegrated debugging tools

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Why VB.NET (cont.)

Why not C#VB.NET----The most productive tool for

building .NET-connected applications. ----Microsoft Corporation

Root in Basic, the most pure-flavor languageproduct from MS.

Easier for VB programmers: a number of uniquefeatures.

E.g.: Only VB.NET has background compilation,dropdown list of the code window.

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What is New in VB.NET ----ForExperienced VB Programmers

IDE changesProject ChangesWeb Changes

WebClass ChangesData ChangesComponent Authoring ChangesUserControl ChangesForms ChangesDebugging ChangesSetup and Deployment ChangesInternational ChangesWindows API ChangesRegistry Access ChangesConstant Changes

Namespace ChangesRun-Time Chan es MELJUN CORTES


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Overview of Big Changes inVB.Net

Everything is object-oriented: abstraction,inheritance, overloading, encapsulation and

polymorphism.(Note: no multipleinheritance, but interfaces supported.)

Multithreaded applications are possible.

Language syntax changes

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Changes in VB Language

All data are objects, based on the class:System.Object.

E.g. class supports Windows forms:System.Windows.Forms.Form.

The built-in VB functionality isencapsulated in a namespace called System.

E.g Collectionhas be replaced bySystem.Collections.

Old control are gone, and new ones haveappeared.

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Changes in VB Language (cont.)

Many keywords are renamed or gone, whilesome new added.

E.g. GosubremovedStrict data typing is now enforcedVariable must be declared before used bydefault.

Cannot assign one data type to another, but canuse Ctypeto convert between types.The same as in VC++ and C#.

Structured exception handling:

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When calling procedures, must useparentheses.

Parameters are by default passed by value,instead of by reference.

Supports constructors and destructors for

use when initializing an object of a class.IfThenstatements are now short-circuited.

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A number of new compound operatorsE.g. x+=2

The And, Or, Notand Xoroperators havechanged from bitwise to boolean operators.Meanwhile, the bitwise versions areBitAnd, BitOr, BitNot, and BitXor.

No default property supportedE.g. VB6: TextBox1=Hello

VB.Net: TextBox1.Text=Hello

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Three new datatypes

Char: unsigned 16-bit

Short: signed 16-bit

Decimal: signed 96-

bit (replacesVariant)

Integer Type VB 6.0 VB.NET

8 bit Byte Byte

16 bit Integer Short

32 bit

Long

Integer

64 bit Not Applicable Long

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Changes in Data Handling

A new data-handling model: ADO.NET.Facilitates Web application.Uses XML to exchange data.

COM/DCOM technologies have beenreplaced by .NET framework.Datasets (not record sets now) are basedon XML schema, so they are strongly

typed.Many new tools are provided to handledata.But can still work with ADO using COMinteroperabilityin the .NET framework.MELJUN CORTES


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Changes in Web Development

Two major types of Web application:Web forms: web-based applications with

GUI.Based on ASP.NETCan use standard HTML control, or newServer control handled by the Web server.

Controls can be bound on a Web form bysetting the codes in the properties.

Web services: to process data usingHTTP and XML files on the Internet.

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Update to VB.NET ?

Visual Basic .NET represents a majordeparture form previous versions of Visual

Basic in several ways.----Microsoft CorporationPlenty changes in VB.NET will take lots ofeffort of even the experienced VB

developers.Old but running fine systems, fund,experienced developers

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Update to VB.NET ? (cont.)

ConsiderationUnsupported features

OLE Container ControlDynamic Data ExchangeDAO or RDO Data BindingVB5 Controls

DHTML ApplicationsActiveX DocumentsProperty Pages

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Carefully reworkedSingle-tier Database Applications

VB Add-insGames

Graphics

Drag and Drop Functionality

VariantsWindows APIs

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Visual Basic Upgrade WizardAutomatically invoked when open a VB6

project.Results are not satisfactory due to thebig different.

Recoding by hand.

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VB.NET Language Essential ----For Non-VB Programmers

Projects TypesThree most commonly used:

Windows FormsWeb Forms

Console Applications

Statements

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Statement: IfElse

Module Module1Sub Main()

Dim intInput As Integer

System.Console.WriteLine(Enter an interger)intInput=Val(System.Console.ReadLine())If intInput=1 Then

System.Console.WriteLine(Thank you!)ElseIf intInput=2 Then

System.Console.WriteLine(Thats good!)

ElseSystem.Console.WriteLine(Not a right number!)

End IfEnd Sub

End Module

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Statement: Select CaseModule Module1Sub Main()

Dim intInput As IntegerSystem.Console.WriteLine(Enter an interger)intInput=Val(System.Console.ReadLine())Select Case intInput

Case 1System.Console.WriteLine(Thank you!)

Case 2System.Console.WriteLine(Thats good!)

Case 3 To 7System.Console.WriteLine(OK)

Case Is> 7System.Console.WriteLine(Too Big)

Case ElseSystem.Console.WriteLine(Not a right number!)

End SelectEnd Sub

End Module MELJUN CORTES


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Functions: Switch and Choose

Switch FunctionSyntax

Switch(expr1, value1[, expr2, value2[,exprn, valuen]])

E.g.intAbsValue=Switch(intValue=0, intValue)

Choose FunctionSyntax

Choose(index, choice1[, choice2,[,choicen]])Note: unlike array index, choose index from 1 to n

E.g.

Str=Choose(intValue, Thank you!, That is good!)MELJUN CORTES


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Loop Statement: Do

Syntax:Do [While|Until] condition]

[statements][Exit Do]

[statements]Loop

E.g.Module Module1

Sub Main()Dim strInput As StringDo Until Ucase(strInput)=Stop

System.Console.WriteLine(What should I do?)strInput=System.Console.ReadLine()

LoopEnd Sub

End Module

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Loop Statement: For

Syntax:For index=startTo end[Step step]

[statements][Exit For]

[statements]Next [index]

E.g.Module Module1

Sub Main()Dim loopIndex As IntegerFor loopIndex=0 to 3

System.Console.WriteLine(Hello!)Next loopIndex

End SubEnd Module

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Loop Statement: While

Syntax:While condition

[statements]End While

E.g.Sub CheckWhile()

Dim intCounter As Integer =0Dim intNumber As Integer =10While intNumer>6

intNumber-=1intCounter+=1

End WhileMsgBox(The loop ran & intCounter & times.)

End Sub

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Loop Statement: For EachNext

Syntax:For Each elementIn group

[statements][Exit For]

[statements]Next element

E.g.Sub Main()

Dim intArray(2), intItem As IntegerintArray(0)=0intArray(1)=1intArray(2)=2For Each intItem In intArray

System.Console.WriteLine(intArray)Next intItem

End Sub

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Like a Loop: With

Syntax:With object

[statements]

End WithE.g.

With TextBox1

,Height = 1000

.Width = 3000

.Text = Welcome, World!End With

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Like With: Enumerations

E.g.Module Module

Enum Days

Sunday=1Monday=2Tuesday=3Wednesday=4

End Enum

Sub Main()System.Console.WriteLine(Monday is day & Days.Monday)

End SubEnd Module

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Option Statement

Option Explicit: On/Off.On:requires declaration of all variables beforeused.

Option Compare: Binary/Text.Specifies strings are compared using binary ortext comparison operations.

Option Strict: On/Off.On:used when assigning a value of one type toa variable of another type, indicates anypossibility of data loss.

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Example for Option Strict

Option Strict On

Module Module1

Sub Main()

Dim dbData As DoubleDim intData As Integer

dbData=3.14159

intData=Cint(dbData) Not intData=dbData

System.Console.WriteLine(intData:&_Str(intData))

End Sub

End Module

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Imports Statement

To import a namespace .

E.g.

Option Strict OffImports System.Console

Module Module1

Sub Main()

WriteLine(Hello!)

End Sub

End Module

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References

Steven Holzner, Visual Basic.NETBlack Book, The Coriolis Group, LLC,

2001.http://msdn.microsoft.com/vbasic

http://www.dotnet247.com

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Thank you!

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