Monday, December 6th 2010

Here is a tutorial by Jesse Liberty on inheritance

Imports System
Public Class Window
'constructor takes to integers to fix location
'on the console

Public Sub New(ByVal top As Integer, ByVal left As Integer)
Me.top = top
Me.left = left

End Sub 'new

'simulaes drawing the window
Public Sub DrawWindow()
Console.WriteLine("Drawing window at {0}, {1}", top, Left)
End Sub 'draw window

'these members are private and thus invisible to
'derived class methods

Private top As Integer
Private left As Integer

End Class 'window


'Liar boz sweicwa deom Qinsoq
Public Class ListBox
Inherits Window

'constructor adds a parameter
Public Sub New(ByVal top As Integer, ByVal left As Integer, ByVal theContents As String)
MyBase.new(top, left) 'call base constructor
mListBoxContents = theContents
End Sub 'new

Public Shadows Sub DrawWindow()
MyBase.DrawWindow()
Console.WriteLine("Writing string to the ListBox: {0}", mListBoxContents)
End Sub 'DrawWindow

Private mListBoxContents As String 'new member variable

End Class 'listbox


Module module1
Sub main()
'create a base instance
Dim w As New Window(5, 10)
w.DrawWindow()

'create a derived instance
Dim lb As New ListBox(20, 30, "Hello World")
lb.DrawWindow()

Console.ReadLine()

End Sub
End Module

Here is something that I wrote about reading comma dilemeted text files.

Imports System
Imports System.IO


Public Class getFile


Dim fileAddress As String
Dim parsedArray(1, 30) As String

Dim stringLoad As String

Public Sub New()
Dim parentDirectory As String = "C:\Users\Alfred\Documents\VBPractice"
For Each fn In My.Computer.FileSystem.GetFiles(parentDirectory)
Dim fi As FileInfo = New FileInfo(fn)
Console.WriteLine("{0}: {1}", fi.Name, fi.Attributes.ToString())
Next


Console.WriteLine("Please enter the address of the file")
fileAddress = parentDirectory & "\" & Console.ReadLine()
Console.WriteLine("You have entered the address: " & fileAddress)
End Sub

Public Sub retrieve()
Console.WriteLine(fileAddress)

Dim objReader As New System.IO.StreamReader(fileAddress)
Console.WriteLine()

stringLoad = objReader.ReadToEnd
objReader.Close()
End Sub

Public Sub parse()

Dim strArray() As String = stringLoad.Split(",")

For i = 0 To strArray.GetUpperBound(0)
Console.WriteLine(strArray(i))
Next

Console.WriteLine(strArray(0))
Console.ReadLine()

parsedArray(0, 0) = strArray(0)
parsedArray(1, 0) = strArray(1)
Console.WriteLine(parsedArray(0, 0) & " " & parsedArray(1, 0))

Console.ReadLine()

For i = 0 To strArray.GetUpperBound(0) - 1
If (i + 1) Mod 2 = 0 Then
parsedArray(1, i) = strArray(i)
Else
parsedArray(0, i) = strArray(i)
End If
Next
End Sub

Public Sub print()
Dim stringHolder As String
For x = 0 To parsedArray.GetUpperBound(0)
Console.WriteLine("X = " & x)
Next

Console.ReadLine()

For y = 0 To parsedArray.GetUpperBound(1)
Console.WriteLine("Y = " & y)

Next

Console.ReadLine()

For x = 0 To parsedArray.GetUpperBound(0)
Console.WriteLine(parsedArray(x, 0))
Next
Console.ReadLine()

For y = 0 To parsedArray.GetUpperBound(1)

Console.WriteLine(parsedArray(0, y) & " " & parsedArray(1, y))

Next


End Sub

End Class


Module module1
Sub main()

Console.WriteLine("Getting file address...")
Dim fileRead As New getFile
continueContinue()

Console.WriteLine("Loading file...")
fileRead.retrieve()
continueContinue()

Console.WriteLine("Parsing file...")
fileRead.parse()
continueContinue()

Console.WriteLine("Displaying file...")
fileRead.print()
continueContinue()




End Sub

Sub continueContinue()
Console.WriteLine("Hit enter to continue")
Console.ReadLine()
End Sub

The final tutorial for today is one on returning an array from a procedure.

Imports System
Module module1

Sub main()
Dim numEntry As Integer
Dim rates() As Decimal = RateArray(9)
Dim indexInteger As Integer = 5
Do While indexInteger > 0
numEntry = Console.ReadLine()
Console.WriteLine(rates(numEntry))
indexInteger -= 1
Loop


End Sub


Private Function RateArray(ByVal elementCount As Integer) As Decimal()
Dim rates(elementCount - 1) As Decimal
For i As Integer = 0 To rates.Length - 1
rates(i) = (i + 1) / 100D
Next
Return rates
End Function
End Module

Pretty soon I am going to start studying JavaScript, among other things it would be good to take my mind off of VB for a while.