Visual Basic

10-May-10 8:42

Hi, I am newbie here; I hope that I am posting correctly. If not please let me know and I will fix that after this post... So here is my dilemma. Thank you for any help in advance. Smile | :)

The program loads; I can pick a ticket type and the appropriate seats are listed in lstbox. I can type in how many ticket I want and clear the form. The Calculate cost button appears to do nothing at all. VB editor does not even give me an error; it just doesn't do anything. This was a homework, I have already handed it in though as is, so now I am just looking for guidance on where I went wrong. I don't want to move onto the next subject if I can't understand this one.

Purpose: This application allows the user to unput data about
' the purchase of baseball tickets. Once the data is entered,
' the program will compute the cost of the tickets purchased.

Option Strict On

<pre>Public Class frmBaseBallTicketSales
    'Class Variables
    Private _decSeasonBoxSeat As Decimal = 2500D
    Private _decSeasonLowerSeat As Decimal = 1500D
    Private _decSingleBoxSeat As Decimal = 55D
    Private _decSingleLowerSeat As Decimal = 35D
    Private _decUpperSeat As Decimal = 25D
    Private _decStanding As Decimal = 15D
    Private _strSeasonBoxSeats As String = "Box Seats $2500"
    Private _strSeasonLowerDeck As String = "Lower Deck Seats $1500"
    Private _strSingleBoxSeats As String = "Box Seats $55"
    Private _strSingleLowerDeck As String = "Lower Deck Seats $35"
    Private _strUpperDeck As String = "Upper Deck Seats $25"
    Private _strSRO As String = "Standing Room Only $15"

Private Sub cboTicketType_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboTicketType.SelectedIndexChanged
'This event handler allows the user to enter choices on form.
'Then it calls subprocesures to place seats in list box.

Dim intTicketChoice As Integer
intTicketChoice = Me.cboTicketType.SelectedIndex
Me.lstSeats.Items.Clear()
Select Case intTicketChoice
Case 0
SeasonTickets()
Case 1
SingleGameTickets()
End Select

'Make items visible in window.
        Me.lblNumberOfTickets.Visible = True
        Me.txtNumberOfTickets.Visible = True
        Me.lblSeatType.Visible = True
        Me.lstSeats.Visible = True
        Me.btnTicketCost.Visible = True
        Me.btnClear.Visible = True
        Me.lblCost.Visible = True
        'clear labels
        Me.txtNumberOfTickets.Text = ""
        Me.lblSeatType.Text = ""
        Me.lblCost.Text = ""
        'set focus
        Me.txtNumberOfTickets.Focus()

    End Sub

Private Sub SeasonTickets()
        'This procedure fills in the possible seat types for season tickets.
        Me.lstSeats.Items.Add(_strSeasonBoxSeats)
        Me.lstSeats.Items.Add(_strSeasonLowerDeck)
    End Sub
    Private Sub SingleGameTickets()
        'This procedure fills in seat types for single game tickets
        Me.lstSeats.Items.Add(_strSingleBoxSeats)
        Me.lstSeats.Items.Add(_strSingleLowerDeck)
        Me.lstSeats.Items.Add(_strUpperDeck)
        Me.lstSeats.Items.Add(_strSRO)
    End Sub

Private Sub btnTicketCost_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTicketCost.Click
        'This event handler determines the cost of the tickets chosen.
        'Then it displays the total cost.

        Dim intNumberTix As Integer
        Dim blnNumberTixIsValid As Boolean = False
        Dim blnSeatTypeIsSelected As Boolean = False
        Dim intSeatType As Integer
        Dim strSelectedSeat As String = ""
        Dim decTotalCost As Decimal

        'Call a function to ensure number of tickets is valid.
        blnNumberTixIsValid = ValidateNumberTix()
        'Call a function to make sure ticket type selected.
        intSeatType = ValidateSeatSelection(blnSeatTypeIsSelected, strSelectedSeat)
        'If the number of tickets ordered is valid, calculate the cost.
        If (blnNumberTixIsValid And blnSeatTypeIsSelected) Then
            intSeatType = Me.cboTicketType.SelectedIndex
            Select Case intSeatType
                Case 0
                    decTotalCost = SeasonTicketsFindCost(intSeatType, _
                                                         intNumberTix)
                Case 1
                    decTotalCost = SingleTicketsFindCost(intSeatType, _
                                                         intNumberTix)
            End Select
            'Display Cost.
            lblCost.Text = & decTotalCost.ToString("C")
        End If

    End Sub

Private Function ValidateNumberTix() As Boolean
        'This function validates value entered for number of tickets.
        Dim intNumberOfTix As Integer
        Dim blnValidityCheck As Boolean = False
        Dim strTicketNumberErrorMessage As String = _
        "Please enter the number of tickets you would like to buy (1-20)"
        Dim strMessageBoxTitle As String = "Error"

        Try
            intNumberOfTix = Convert.ToInt32(Me.txtNumberOfTickets.Text)
            If intNumberOfTix > 0 And intNumberOfTix < 21 Then
                blnValidityCheck = True
            Else
                MessageBox.Show(strTicketNumberErrorMessage, _
                strMessageBoxTitle)
                Me.txtNumberOfTickets.Focus()
                Me.txtNumberOfTickets.Clear()
            End If
        Catch Exception As FormatException
            MessageBox.Show(strTicketNumberErrorMessage, _
                            strMessageBoxTitle)
            Me.txtNumberOfTickets.Focus()
            Me.txtNumberOfTickets.Clear()
        Catch Exception As OverflowException
            MessageBox.Show(strTicketNumberErrorMessage, _
                            strMessageBoxTitle)
        Catch Exception As SystemException
            MessageBox.Show(strTicketNumberErrorMessage, _
                            strMessageBoxTitle)
            Me.txtNumberOfTickets.Focus()
            Me.txtNumberOfTickets.Clear()
        End Try

        Return blnValidityCheck

    End Function

Private Function ValidateSeatSelection(ByRef blnType As Boolean, _
                                           ByRef strType As String) As Integer
        'This function makes sure user sleects a seat type.
        Dim intSeatType As Integer
        Try
            intSeatType = Convert.ToInt32(Me.lstSeats.SelectedIndex)
            strType = Me.lstSeats.SelectedItem.ToString()
            blnType = True
        Catch Exception As SystemException
            'Detects if seat type not selected.
            MessageBox.Show("Select a seat type", "Error")
            blnType = False
        End Try
        Return intSeatType

    End Function

Private Function SeasonTicketsFindCost(ByVal intSeatType As Integer, _
                                           ByVal intNumberTix As Integer) As Decimal
        'This function will calculate cost of season tickets.
        Dim decTotalCost As Decimal
        Dim decSeatCost As Decimal
        Dim decNumberTix As Decimal

        Select Case intSeatType
            Case 0
                decSeatCost = _decSeasonBoxSeat
                decNumberTix = intNumberTix
            Case 1
                decSeatCost = _decSeasonLowerSeat
                decNumberTix = intNumberTix
        End Select
        decTotalCost = decSeatCost * decNumberTix
        Return decTotalCost

    End Function

Private Function SingleTicketsFindCost(ByVal intseattype As Integer, _
                                           ByVal intNumberTix As Integer) As Decimal
        'This function will calvulate the cost of single tickets.
        Dim decTotalCost As Decimal
        Dim DecSeatCost As Decimal
        Dim decNumberTix As Decimal

        Select Case intseattype
            Case 0
                DecSeatCost = _decSingleBoxSeat
                decNumberTix = intNumberTix
            Case 1
                DecSeatCost = _decSingleLowerSeat
                decNumberTix = intNumberTix
            Case 2
                DecSeatCost = _decStanding
                decNumberTix = intNumberTix
            Case 3
                DecSeatCost = _decUpperSeat
                decNumberTix = intNumberTix
        End Select
        decTotalCost = DecSeatCost * intNumberTix
        Return decTotalCost

    End Function

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        'This event handler clears the form and resets the form for reuse,
        'when user clicks the clear button.
        Me.cboTicketType.Text = "Select Ticket Type"
        Me.txtNumberOfTickets.Clear()
        Me.lstSeats.Items.Clear()
        Me.lblCost.Visible = False
        Me.lblTotalCost.Visible = False

    End Sub

 Private Sub frmBaseBallTicketSales_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'This handler creates 5 seconds for the splash screen
        Threading.Thread.Sleep(5000)
    End Sub

End Class

Hope I did this right.

modified on Monday, May 10, 2010 3:27 PM

DJ Matthews10-May-10 9:11

DJ Matthews

10-May-10 9:11

It would be nice if you would put your code in some <pre></pre> tags so it easy to read.

dorkpixie10-May-10 9:19

10-May-10 9:19

I have no idea how to use those tags. When I said newbie I meant very new. Like a baby just born.

DJ Matthews10-May-10 9:21

DJ Matthews

10-May-10 9:21

Do this when you edit your message:

<pre>

**Your code here**

</pre>

Wes Aday10-May-10 9:26

10-May-10 9:26

Edit your post. Select the code segments then click on the "code block" link on the line above Smile | :)

Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
Individuality is fine, as long as we do it together - F. Burns

dorkpixie10-May-10 9:33

10-May-10 9:33

Thank you very much!! I got it, I think.

Wes Aday10-May-10 9:40

10-May-10 9:40

You're welcome. Looks much more gooder Smile | :)

Luc Pattyn10-May-10 9:13

Luc Pattyn

10-May-10 9:13

I second that; it is unreadable right now. You could still edit the existing message though.

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

dorkpixie10-May-10 9:18

10-May-10 9:18

When I pasted the code it was indented. I do not know how to indent other than using the tab key... I'm sorry.

Luc Pattyn10-May-10 9:32

Luc Pattyn

10-May-10 9:32

outside of PRE tags, tabs are just spaces, and multiple spaces get ignored. Inside PRE tags, it all works pretty much like in a code editor.

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

I only read formatted code with indentation, so please use PRE tags for code snippets.

I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).

Wes Aday10-May-10 9:21

10-May-10 9:21

dorkpixie wrote:
appears to do nothing at all

What does that mean? You click the button and no code runs? You click the button and the code runs but gives no output?

Have you stepped through the code using the debugger?

dorkpixie10-May-10 9:35

10-May-10 9:35

Click the button and get no output at all. No errors either. Weirdest non running code I have ever written.

Wes Aday10-May-10 9:39

10-May-10 9:39

Okay if you click the button and no code runs at all, check that the button is actually hooked up to the function through the Events property sheet.

If the button is hooked to the event handler then set a breakpoint in the event handler and step through the code until you narrow down where the problem is.

DaveAuld10-May-10 10:11

DaveAuld

10-May-10 10:11

1) in your btnTicketCost, and an else clause to the If block, and display a validation error message, your Validate Ticket might never be returning True, hence never resulting in any output.

2) If #1 above never returns True, start putting debug statements in the function to try and establish which part(s) is/are causing the validation to fail.

Dave

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William Winner10-May-10 10:51

William Winner

10-May-10 10:51

First, they told you about the pre tag, but what they didn't tell you was that you can specify which language you're using which helps with the coloring. In your case, you're pre tags should look like:
<pre lang="vbnet">

Beyond that, I'll just comment on what I see...
I don't know if your assignment was to use decimal types or not, but it doesn't look like it's necessary since you're dealing wholly with integer values and should never get any decimal values.

I also don't know if you were told to use Select Case statements, but you can use If/Else if they're small statments...for instance you wrote:

Select Case intTicketChoice
   Case 0
      SeasonTickets()
   Case 1
      SingleGameTickets()
End Select

which is a total of 11 words and 78 characters.

If intTicketChoice = 0 Then
    SeasonTickets()
Else
    SingleGameTickets()
End If

is 10 words and 66 characters. Also, the If/Else should be streamlined as far as the number of cycles it takes to evaluate since I assume the Select Case just builds a series of If/ElseIf statements.

Let's start with btnTicketCost_Click. You have some strange code here. First, what is it that it needs to do? Well, it looks like it needs to check to make sure that a ticket type was selected and that an appropriate number of tickets were selected for purchase and then adds up the total. So what is it that you actually do? You create intNumberTix, but then you never set it to anything. You then run a function to validate the number of tickets. That checks to see if the number in the TextBox was between 1 and 20. If it isn't, you show a MessageBox asking them to re-enter the number of tickets, I guess.

First, that ValidateNumberTix is way too long. It could just be:

Private Function ValidateNumberTix() as Boolean
   If Not IsNumeric(Me.txtNumberOfTickets.Text) Then
       ResetNumberTix()
       Return False
   Else
      Dim intNumberTix As Long = CLng(Me.txtNumberOfTickets.Text)
      If intNumberTix < 1 Or intNumberTix > 20 Then
          ResetNumberTix()
          Return False
      End If
   End If
   Return True
End Function

Private Sub ResetNumberTix()
   MessageBox.Show("Please enter the number of tickets you would like to buy (1-20)", "Error")
   Me.txtNumberOfTickets.Focus()
   Me.txtNumberOfTickets.Clear()
End Sub

You create extra variables in memory that you don't need which take extra cycles.
Back to btnTicketCost_Click. You can first just check if the number of tickets is valid and if it isn't, exit the sub. Then, you can check if the user made a ticket type selection. You can do this a lot simpler than you did. First, just check if there were any selected items using

If lstSeats.SelectedItems.Count = 0 Then 
   MessageBox.Show("Select a seat type", "Error")
   Return
End If

Then, just make a function to return the seat type. (As an FYI, naming a method using the phrase "Validate" implies it will return a boolean. Using proper naming conventions can really help when trying to figure out what you did later). You passed into ValidateSeatSelection a variable name strSelectedSeat, which you then never used again. Once again, another unnecessary variable. You also set intSeatType twice.
I'm also quite confused about what values can be in intSeatType. Initially, you just check for 0 and 1. If it's 0, you go to SeasonTickets, if it's 1, SingleTickets. But, then within each of those function, you re-evaluate intSeatType and it apparently has a different meaning. I think you used the same variable name to check if it's supposed to be season tickets or single tickets, and for what type of seat it is.

I would rewrite it to something more like:

'Check if the number of tickets is valid
If Not ValidateNumberTix() Then Return

'Check if the user selected a seat type
If lstSeats.SelectedItems.Count = 0 Then 
   MessageBox.Show("Select a seat type", "Error")
   Return
End If

Dim intSeatType As Integer = Me.cboTicketType.SelectedIndex
Dim lngTotalCost as Long
If intSeatType = 0 Then
   lngTotalCost = SeasonTicketsFindCost(lstSeats.SelectedIndex, _
                                        CInt(Me.txtNumberOfTickets.Text))
Else
   lngTotalCost = SingleTicketsFindCost(lstSeats.SelectedIndex, _
                                        CInt(Me.txtNumberOfTickets.Text))
End If

lblCost.Text = String.Format("{0:C}",lngTotalCost)

Again, Decimal is really only needed when dealing with cents. When dealing with whole numbers, you shouldn't see any problems with multiplication. Decimal takes a lot more overhead and is a lot slower than just using a long or integer.

And, instead of sleeping the thread for the splash screen, you would be better off using a Timer. If the user clicks on the splash screen during that 5 seconds, it could end up looking funny. Just use a timer, set it to tick every 5000 milliseconds and when the timer ticks, just close the form.

dorkpixie11-May-10 6:53

11-May-10 6:53

There's a couple of things... You're help is awesome and easy to understand.
However, since this is still a beginner VB class there are some things we have not been taught to use yet such as: Dim intNumberTix As Long = CLng(Me.txtNumberOfTickets.Text)
have no idea what Long and CLng is.. and If lstSeats.SelectedItems.Count = 0 Then, we have not done counts yet. So while I generally understand what this means:
If intSeatType = 0 Then
lngTotalCost = SeasonTicketsFindCost(lstSeats.SelectedIndex, _
CInt(Me.txtNumberOfTickets.Text))
Else
lngTotalCost = SingleTicketsFindCost(lstSeats.SelectedIndex, _
CInt(Me.txtNumberOfTickets.Text))
End If

lblCost.Text = String.Format("{0:C}",lngTotalCost)

I have never seen lng or Long as a variable type. I can however take what you have given me and put it into what we have learned.
Sometimes in the introductory courses they kind of force you to use certain things. Such as the way the splash screen is timed. I am glad though that I have gotten feedback from others who have more experience so that I do not miss these lessons. Hopefully classes will get to them so I don't graduate with completely wrong information. Thank you again for your help. Do you want me to post working code when I finish it?

William Winner11-May-10 7:08

William Winner

11-May-10 7:08

Hmm...that's curious...you were taught about Decimals before Longs? A Long is just a larger Integer. Decimal is definitely not a standard type. The 4 standard VB numeric types are Integer, Long, Float, and Double. An Int is only good up to 32,767. A Long goes beyond that. CLng is just a conversion method. There are many of these...CInt, CDec, CLng, CDbl...So, if you pass in a string value to any of them, it will try to return whatever number is in that string in the selected type. Or it you pass an Integer into CDbl, it will return that Integer as a Double.

As far as the SelectedItems.Count, that is just a property within the ListBox. I assume that since you are allowed to use a ListBox, you should be allowed to use any of its methods. That is just one of them.

But, I know about profs not wanting you to skip ahead. In one of my classes, I read ahead and found the switch in C++ (the same as VB's Select) and used it instead of a series of for loops and was told that I wasn't to use something we hadn't been taught yet.

And you may not feel like you need one, but when I was in college, I was a tutor and I hope that it helped the people that I tutored. Normally, schools provide the service free of charge and it can be really helpful to have someone who's gotten further helping you understand how to structure a program and even giving hints on what has worked for them and what hasn't.

dorkpixie11-May-10 7:34