[Year 12 SofDev] Queues in VB.net

[BUCKNELL, Chris]

Hi Trav,

Here's a little queue example that I've used

Regards Chris



Module Module1

    Sub Main()
        Dim getYourBurger As New HomeMadeQueue

        'Add some people to the queue
        Console.WriteLine("Add 'Chris' to the Queue")
        getYourBurger.EnQueue("Chris")
        Console.WriteLine("Add 'Jill' to the Queue")
        getYourBurger.EnQueue("Jill")
        Console.WriteLine("Add 'Ted' to the Queue")
        getYourBurger.EnQueue("Ted")
        Console.WriteLine("Add 'Mel' to the Queue")
        getYourBurger.EnQueue("Mel")

        'How long is that queue?
        Dim numberPeopleInQueue As Integer = getYourBurger.Count
        Console.WriteLine("Queue length is:" & numberPeopleInQueue)

        'Who is first in line?
        Console.WriteLine("The first in line is:" & getYourBurger.Peek)

        'Process the queue ... do you want fries with that???
        For counter As Integer = 1 To numberPeopleInQueue
            Console.WriteLine("Hi " & getYourBurger.DeQueue() & ", what burger would you like?")
        Next

        'What happens if we try to process an empty queue
        Console.WriteLine("Is there anybody out there??? " & getYourBurger.DeQueue())

        Console.ReadLine()

    End Sub

    ''' <summary>
    ''' The following Queue class implementation includes methods for EnQueue,
    ''' DeQueue, ClearQueue (clearing the queue), Peek, and Count, as well as a
    ''' default constructor for the class.
    '''
    ''' The underlying data structure used to hold the queue data is an ArrayList.  This is
    ''' used because their dynamic nature, i.e. Insert is added to the next free element of the list,
    ''' remove from front automatically moves each item in the list up one element, and we don't need
    ''' to maintain any placeholders (first item, last item etc...)
    '''
    ''' </summary>
    ''' <remarks>This is closely based on content from "Data Structures and Algorithms Using Visual Basic.NET"
    '''  by Michael McMillan (ISBN:9780521547659)
    ''' </remarks>
    Public Class HomeMadeQueue
        Private _queue As New ArrayList()
        Public Sub New()
            MyBase.New()
        End Sub
        Public Sub EnQueue(ByVal item As Object)
            _queue.Add(item)
        End Sub
        Public Function DeQueue() As Object
            Dim item As Object
            If Count() > 0 Then
                item = _queue.Item(0)
                _queue.RemoveAt(0)
            Else
                item = "Queue empty error"
            End If
            Return item
        End Function
        Public Function Peek() As Object
            Return _queue.Item(0)
        End Function
        Public Sub ClearQueue()
            _queue.Clear()
        End Sub
        Public Function Count() As Integer
            Return _queue.Count()
        End Function
    End Class



End Module


From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au] On Behalf Of Travis Parker
Sent: Thursday, 4 August 2011 8:16 AM
To: Year 12 Software Development Teachers' Mailing List
Subject: [Year 12 SofDev] Queues in VB.net


Dear All,

I am currently doing some stuff in data structures and going to create a queue example in VB.net. Does anyone have an example of these? I am thinking that I will use a queue as part of U4O1. I've already done a stack example but am going to write a SAC with a waiting list FIFO so need to use a queue.

Any assistance from the brilliant programmers on the list would be much appreciated and save me some time!

Cheers

Trav
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