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VB .NET Revisit by rgrVhQ3

VIEWS: 14 PAGES: 23

									VB .NET Revisit




     VB .NET Revisit   1
    Software Development Life Cycle
•   Problem Definition
•   Requirement Analysis
•   Systems Design
•   Implementation
•   Testing & Debugging
•   Deployment
•   Maintenance

                   VB .NET Revisit    2
                  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            3
Building HelloWorld with
  Visual Studio .NET




         VB .NET Revisit   4
          Hello World - Console
Imports System           ‘ import System namespace

Public Module Hello     ‘ a Standard Module
  Public Sub Main()
        Console.WriteLine("Hello World!")
  End Sub
End Module


• A Console application
• To compile (by command line compiler):
   – vbc HelloWorld.vb
• To execute:
   – HelloWorld.exe


                             VB .NET Revisit         5
                         Hello World - GUI
Imports System                       ' import System namespace
Imports System.Drawing
Imports 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()        ' constructor
            lblHelloWindows = 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.TopCenter
            End With

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

            Controls.Add(lblHelloWindows)    VB .NET Revisit     6
  End Sub
End Class
          Hello World - GUI
• A Windows Application
• To compile:
  – vbc HelloWorld2.vb
    /reference:System.dll,System.Drawing.dll,Syst
    em.Windows.Forms.dll /target:winexe
• To execute:
  – HelloWorld2.exe


                      VB .NET Revisit           7
                         Class
Public Class Student        ‘ a base class
  …
End Class

Public Class FtStudent
  Inherits Student
  …
End Class

Dim s1 As New Student()
Dim s2 As New FtStudent()
s1 = s2
                         VB .NET Revisit     8
                     Access Modifiers
•     Control the accessibility of types and types members (including fields,
      methods, etc.)


    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.)
•    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

                                    VB .NET Revisit                              9
              Fundamental Types
•   Boolean
•   Byte
•   Short
•   Integer
•   Long
•   Decimal
•   Single
•   Double
•   Char
•   String
•   Date
•   Object
                    VB .NET Revisit   10
           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        11
                  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               12
     Assignment Statements
Dim a, b As SomeClass
a = New SomeClass()
a.MyPublicMember = “value in a”

b=a
b = New SomeClass()


                 VB .NET Revisit   13
                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           14
                          Basic I/O
Module 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                               15
         Branching Statements (1)
•   Call SomeMethod() or
•   SomeMethod()
•   Exit Do, Exit For, Exit Function, Exit Sub, Exit Try

If A = B Then
   statements
End If

If A = B Then
   statements
Else
   statements
End If

If A = B Then
   statements
ElseIf expression Then
   statements
Else
   statements
End If                               VB .NET Revisit       16
    Branching Statements (2)
Select Case strColor
  Case “red”
    …
  Case “green”, “blue”
    …
  Case Else
    …
End Select
                  VB .NET Revisit   17
                                   Loop
Do While I < 10
   …
Loop

Do
   …
Loop Until I >= 10

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

For Each i in iArrary                 ‘ iArrary is an array
   …
Next

For Each obj In col        ‘ col is a collection
   Console.WriteLine(obj.ToString())
Next

                                   VB .NET Revisit            18
                          Array
Dim a(4) As Integer
For i = 0 to 4
  Console.WriteLine(a(i))
Next

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

Dim a() As String = {“First”, “Second”, “Third”}
Dim a(5,10) As Integer
                          VB .NET Revisit          19
                    Enumeration
Module 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                20
                             Structure
Module 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              21
                        Collection
Dim col As New Collection()
col.Add(“First item”)
col.Add(“Second item”)
col.Add(“Third item”)

Dim obj As Object
For Each obj In col
   Console.WriteLine(CType(obj, String))
Next

Dim i As Integer
For i = 1 to col.Count
   Console.WriteLine(CType(col(i), String))
Next

                              VB .NET Revisit   22
             Sub & Function
Sub CheckInput()
  …
End Sub

Function Square(ByVal i as Integer) As Integer
  …
  Return x
End Function

                     VB .NET Revisit             23

								
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