Help with very basic coding

[TiffanyP]

Hello everyone. I have been assigned as a "Final" to code a Visual Basic program that takes concession stand orders, adds the items to a list, then figures the change.

This is a picture of the interface I designed to give you all the right idea.

    Private Sub xAddHamburgerButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles xAddHamburgerButton.Click
        Dim total As Double

        Double.TryParse(Me.xTotalLabel.Text, total)

        total = total + 2

        Me.xTotalLabel.Text = total.ToString("C2")

        Me.xItemsListBox.Items.Add("Hamburger   $2.00")
    End Sub

This code works to a point. It adds the $2.00 in the total box, but keeps it there even if I press the "add" button next to "hamburger" again. I would like that total to stack every time I press the button so it keeps a running total of everything purchased(and go on when I add other items, like "pizza" to the listbox).

Also this code isn't doing what is desired.

    Private Sub xChangeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles xChangeButton.Click
        Dim amount As Integer
        Dim total As Integer
        Dim change As Integer

        Integer.TryParse(Me.xAmountRecievedTextBox.Text, amount)
        Integer.TryParse(Me.xTotalLabel.Text, total)
        Integer.TryParse(Me.xChangeLabel.Text, change)

        change = amount - total

        Me.xChangeLabel.Text = change.ToString("C2")
    End Sub

This picture demonstrates what happens:

And one last thing. What code would I use to make it remove a selected item from the list box? (xItemsListBox)

Any help would be greatly appreciated. Sorry if I sound like a newbie... but I am.

[.paul.]

for your add to total button:

Double.TryParse(Me.xTotalLabel.Text.replace("$",""), total)

for your change button, integers are whole numbers. you need to use doubles or decimals.

[formlesstree4]

This code works to a point. It adds the $2.00 in the total box, but keeps it there even if I press the "add" button next to "hamburger" again. I would like that total to stack every time I press the button so it keeps a running total of everything purchased(and go on when I add other items, like "pizza" to the listbox).

after each button click for adding or subtracting, and modifying the variable, set the label to the value again.

total = total + <amount here>
labelnamehere.text = total

[TiffanyP]

This code works to a point. It adds the $2.00 in the total box, but keeps it there even if I press the "add" button next to "hamburger" again. I would like that total to stack every time I press the button so it keeps a running total of everything purchased(and go on when I add other items, like "pizza" to the listbox).

after each button click for adding or subtracting, and modifying the variable, set the label to the value again.

total = total + <amount here>
labelnamehere.text = total

That mostly works, but I need it do display in currency. Still closer than I was.

Thanks

Edit: Never mind. It works now. I just accidentally deleted a line.

[Shaggy Hiker]

Decimal will work better than either integer or double for dealing with currency. Not sure if you still have a question, though.

I also noted that you were declaring total as a local variable in the sub, which means that each time the sub is entered, the variable will be reset to 0, so there isn't any point in adding 2 to it. You might as well just set it to 2. It certainly appears that total should be declared outside of the sub at form scope.

[Vectris]

You do know that your "total" variable will not hold any decimal numbers? Meaning if you add a hamburger that is 1.50 to it, then the total will read 2 because Integers don't hold decimals so they automatically round.

Instead, make all of your number variables Decimals, then when you want to output the total, use:

total.ToString("C2")

And it will display in US Currency mode. Also, I suggest you turn Option Strict On to avoid conversion errors.

[TiffanyP]

You do know that your "total" variable will not hold any decimal numbers? Meaning if you add a hamburger that is 1.50 to it, then the total will read 2 because Integers don't hold decimals so they automatically round.

Instead, make all of your number variables Decimals, then when you want to output the total, use:

total.ToString("C2")

And it will display in US Currency mode. Also, I suggest you turn Option Strict On to avoid conversion errors.

Ah! Of course! Thank you much. I'm not entirely sure how I over looked that.

Decimal will work better than either integer or double for dealing with currency. Not sure if you still have a question, though.

I also noted that you were declaring total as a local variable in the sub, which means that each time the sub is entered, the variable will be reset to 0, so there isn't any point in adding 2 to it. You might as well just set it to 2. It certainly appears that total should be declared outside of the sub at form scope.

I did have one more question in the post about removing items from the list box. It need to be set up that when you remove an item from a list box, the cost of that item also subtracts from the total. Any ideas?

Sorry about all the questions. :/

[Vectris]

Will the cost always be at the end like this?
Hamburger $2.00

You can use IndexOf and pull it out of the text like

Dim Cost as Decimal
Dim theItem as String = ListBox1.SelectedText
ListBox1.Items.Remove(ListBox1.SelectedIndex)
Cost = CDec(theText.Substring(theText.IndexOf("$") + 1))

And then subtract Cost from your total.

[formlesstree4]

Simple Idea:
Use two labels for the total cost:
1 label is the $ symbol
the other is the actual amount. Would make stuff alot easier.

As for subtraction:

value = value - amounthere
labelname.text = value

[formlesstree4]

Here's an example of some code I just tested for an add and remove button:

Private Sub chsburgrAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chsburgrAdd.Click
        foodListBox.Items.Add("Cheeseburger: $2.50")
        totalMoney += 2.5
        finalCostLbl.Text = "$" & totalMoney
    End Sub
 
    Private Sub chsburgrDel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chsburgrDel.Click
        Try
            If foodListBox.Items.Contains("Cheeseburger: $2.50") = True Then
                foodListBox.Items.Remove("Cheeseburger: $2.50")
                If totalMoney <= 0 Then
                    totalMoney = 0.0
                    finalCostLbl.Text = "$" & totalMoney
                Else
                    totalMoney -= 2.5
                    finalCostLbl.Text = "$" & totalMoney
                End If
            Else
                Exit Sub
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

Very rough, but you get the idea of what I mean.

EDIT: 2 things
1. I don't care if its not Option Strict coding.
2. I wrapped it in Try statements because I was guessing my work.

[TiffanyP]

Here's an example of some code I just tested for an add and remove button:

Private Sub chsburgrAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chsburgrAdd.Click
        foodListBox.Items.Add("Cheeseburger: $2.50")
        totalMoney += 2.5
        finalCostLbl.Text = "$" & totalMoney
    End Sub
 
    Private Sub chsburgrDel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chsburgrDel.Click
        Try
            If foodListBox.Items.Contains("Cheeseburger: $2.50") = True Then
                foodListBox.Items.Remove("Cheeseburger: $2.50")
                If totalMoney <= 0 Then
                    totalMoney = 0.0
                    finalCostLbl.Text = "$" & totalMoney
                Else
                    totalMoney -= 2.5
                    finalCostLbl.Text = "$" & totalMoney
                End If
            Else
                Exit Sub
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

Very rough, but you get the idea of what I mean.

EDIT: 2 things
1. I don't care if its not Option Strict coding.
2. I wrapped it in Try statements because I was guessing my work.

This code is amazing to me, and it almost exactly what I wanted. I may be messing it up though, but when I do it if I have more than one cheese burger (say, 3 of them for a total cost of $7.50) the first time it will subtract properly to $5.00, then the second time it will go straight to zero.

Thank you every one who's helped me so far, though. I really appreciate it.

[formlesstree4]

Make sure you aren't skipping any lines. This code doesn't mess up, I've tested it now, using hamburgers too (at $2 dollars) and mixing things up. It appeared to work.

Experiment around with it, see if you can figure out whats going on.

[ForumAccount]

One flaw I see with your UI design, and maybe others will agree, is that you've actually designed the form with the available items on it. The point I'm trying to make is that if the "Concession Stand" adds new items, then you have to go in and add the buttons, the code behind the buttons etc... In OOP design you really want to make stuff like that easy on yourself.

IMO this situation is perfect for a Dictionary(Of String, Decimal). Use two ListBoxes: 1 shows the available items, the other shows what they've chosen. Splitting these two ListBoxes are the [+]/[-] buttons. This is the code I used, I didn't do the amount received, change part. I went up to the subtotal step:

Public Class Form1 
    Private ConItems As New Dictionary(Of String, Decimal) 
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 
        With ConItems 
            .Add("Hamburger (Price: $2.50)", 2.5D) 
            .Add("Hot Dog (Price: $2.00)", 2D) 
            .Add("Chips (Price: $1.25)", 1.25D) 
            'Add items here 
        End With 
        Dim Items(ConItems.Count - 1) As String 
        ConItems.Keys.CopyTo(Items, 0) 
        Me.ltbItemsAvailable.DataSource = Items 
    End Sub 
    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click 
        Me.ltbItemsChosen.Items.Add(Me.ltbItemsAvailable.SelectedItem) 
        Me.lblSubTotal.Text = "Sub Total: $ " & SubTotal.ToString 
    End Sub 
    Private Sub btnRemove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRemove.Click 
        If Me.ltbItemsChosen.SelectedIndex <> -1 Then 
            Me.ltbItemsChosen.Items.RemoveAt(Me.ltbItemsChosen.SelectedIndex) 
        End If 
        Me.lblSubTotal.Text = "Sub Total: $ " & SubTotal.ToString 
    End Sub 
    Private Function SubTotal() As Decimal 
        Dim SubTotalPrice As Decimal = 0D 
        For Each ConItem As String In Me.ltbItemsChosen.Items 
            SubTotalPrice += ConItems(ConItem.ToString) 
        Next 
        Return SubTotalPrice 
    End Function 
End Class

If the Concession Stand adds new items, all you have to do is go to the dictionary and add the item and the associated price. I don't know if your instructor is ok with you using a DataSource, if you're unsure I wouldn't use this code...

[Vectris]

Will the cost always be at the end like this?
Hamburger $2.00

You can use IndexOf and pull it out of the text like

Dim Cost as Decimal
Dim theItem as String = ListBox1.SelectedText
ListBox1.Items.Remove(ListBox1.SelectedIndex)
Cost = CDec(theText.Substring(theText.IndexOf("$") + 1))

And then subtract Cost from your total.

Ummm, have you tried my code??? It's a lot shorter and it will only delete the selected item, not any others even if they are the same item.

[.paul.]

Ummm, have you tried my code??? It's a lot shorter and it will only delete the selected item, not any others even if they are the same item.

Ummm, have you read the documentation for .remove?

.removeat removes by index