VB .NET Revisit 1

VB .NET Revisit

VB .NET Revisit 2

Software Development Life Cycle

• Problem Definition

• Requirement Analysis

• Systems Design

• Implementation

• Testing & Debugging

• Deployment

• Maintenance

VB .NET Revisit 3

VB .NET

• .NET CLR-compliant language• Event-driven• Object Oriented• Visual Studio .NET

– A Rapid Application Development (RAD) environment

– An Integrated Development Environment (IDE)

• Editor, Command Line Compiler

VB .NET Revisit 4

Building HelloWorld with Visual Studio .NET

VB .NET Revisit 5

Hello World - Console

• A Console application• To compile (by command line compiler):

– vbc HelloWorld.vb

• To execute:– HelloWorld.exe

Imports System ‘ import System namespace

Public Module Hello ‘ a Standard Module Public Sub Main()

Console.WriteLine("Hello World!") End SubEnd Module

VB .NET Revisit 6

Hello World - GUIImports System ' import System namespaceImports System.DrawingImports System.Windows.Forms

Public Class HelloWindows Inherits Form ' inherits System.Windows.Forms.Form

Private lblHelloWindows As Label

Public Shared Sub Main()Application.Run(New HelloWindows())

End Sub

Public Sub New() ' constructorlblHelloWindows = New Label()With lblHelloWindows .Location = New Point(37,31) .Size= New Size(392,64) .Font = New Font("Arial",36) .Text = "Hello, Windows!" .TabIndex = 0 .TextAlign = ContentAlignment.TopCenterEnd With

Me.Text = "Visual Basic .NET"AutoScaleBaseSize = New Size(5, 13)FormBorderStyle = FormBorderStyle.FixedSingleClientSize = New Size(466,127)

Controls.Add(lblHelloWindows) End SubEnd Class

VB .NET Revisit 7

Hello World - GUI

• A Windows Application

• To compile:– vbc HelloWorld2.vb /reference:System.dll,Syst

em.Drawing.dll,System.Windows.Forms.dll /target:winexe

• To execute:– HelloWorld2.exe

VB .NET Revisit 8

Class

Public Class Student ‘ a base class…

End Class

Public Class FtStudentInherits Student…

End Class

Dim s1 As New Student()Dim s2 As New FtStudent()s1 = s2

VB .NET Revisit 9

Access Modifiers

• Control the accessibility of types and types members (including fields, methods, etc.)

• Private: accessible only from within the context in which it is declared• Protected: from within the program in which it is defined and the derived

classes• Public: publicly accessible

Public Class SomeClass

Public Sub DoSomething()

End Sub

Private Sub InternalHelperSub()

End Sub

End Class

• Control the accessibility of types and types members (including fields, methods, etc.)

VB .NET Revisit 10

Fundamental Types

• Boolean• Byte• Short• Integer• Long• Decimal• Single• Double• Char• String• Date• Object

VB .NET Revisit 11

Variables, Literals

• Dim bFlag As Boolean = False• Dim datToday As Date = #01/01/2005#• Dim iValue As Integer• Dim lValue As Long• Dim shValue As Short = 128• Dim sngValue As Single• Dim dblValue As Double• Dim MyString As String

VB .NET Revisit 12

Type Conversion• Implicit Type Conversion:

– Char -> String– Byte -> Short -> Integer -> Long -> Decimal -> Single ->

Double• Explicit Type Conversion (Casting):

– CByte()– CShort()– CInt()– CLng()– CDec()– CSng()– CDbl()– CBool()– CChar()– CStr()– CDate()

VB .NET Revisit 13

Assignment Statements

Dim a, b As SomeClass

a = New SomeClass()

a.MyPublicMember = “value in a”

b = a

b = New SomeClass()

VB .NET Revisit 14

Operators

• +, -, *, /• \ (integer division)• Mod (modulo), 9 Mod 2• ^ (exponentiation), X^2• =, <>, <, <=, >, >=, AND, OR, NOT, XOR• TypeOf …Is, TypeOf(x) Is String• Is, s1 Is s2• Like, s1 Like "a*“

VB .NET Revisit 15

Basic I/OModule Module1

Sub Main() Dim n As Integer Dim s As String Console.Out.WriteLine("HelloWorld! What's your name?") s = Console.In.ReadLine() ‘ read in a string Console.Out.WriteLine("How old are you?") n = Console.In.ReadLine() ‘ read in a number Console.Out.WriteLine("Hi " + s + ", you're " + CStr(n) + " already.") ‘ or Console.Out.WriteLine("Hi {0}, you're {1} already.", s, n) Console.In.ReadLine() ‘ wait to press Enter End Sub

End Module

VB .NET Revisit 16

Branching Statements (1)• Call SomeMethod() or• SomeMethod()• Exit Do, Exit For, Exit Function, Exit Sub, Exit Try

If A = B Then statementsEnd If

If A = B Then statementsElse statementsEnd If

If A = B Then statementsElseIf expression Then statementsElse statementsEnd If

VB .NET Revisit 17

Branching Statements (2)

Select Case strColor Case “red”

… Case “green”, “blue”

… Case Else

…End Select

VB .NET Revisit 18

LoopDo While I < 10

…Loop

Do…

Loop Until I >= 10

For i = 0 to 4 Step 2Console.WriteLine(i)

Next

For Each i in iArrary ‘ iArrary is an array…

Next

For Each obj In col ‘ col is a collectionConsole.WriteLine(obj.ToString())

Next

VB .NET Revisit 19

Array

Dim a(4) As IntegerFor i = 0 to 4

Console.WriteLine(a(i))Next

Dim a() As Integera = New Integer(2) {}a(0) = 1a(1) = 2

Dim a() As String = {“First”, “Second”, “Third”}Dim a(5,10) As Integer

VB .NET Revisit 20

EnumerationModule Module1 Enum CardSuit clubs = 0 diamonds = 1 hearts = 2 spades = 3 End Enum Sub Main() Dim cs As CardSuit = CardSuit.hearts System.Console.Out.WriteLine("The value cs is {0}", cs) End Sub End Module

VB .NET Revisit 21

StructureModule Module1 Structure PixelCoord Public x As Single Public y As Single End Structure Sub Main()

Dim p As PixelCoord

p.x = 200 p.y = 100 System.Console.Out.WriteLine("The value p.x is {0}", p.x) System.Console.Out.WriteLine("The value p.y is {0}", p.y) End Sub End Module

VB .NET Revisit 22

CollectionDim col As New Collection()col.Add(“First item”)col.Add(“Second item”)col.Add(“Third item”)

Dim obj As ObjectFor Each obj In col

Console.WriteLine(CType(obj, String))Next

Dim i As IntegerFor i = 1 to col.Count

Console.WriteLine(CType(col(i), String))Next

VB .NET Revisit 23

Sub & Function

Sub CheckInput()

…

End Sub

Function Square(ByVal i as Integer) As Integer

…

Return x

End Function