Option Strict On Getting items from lstBox using loop and index - vb.net

Question

Is there a way to assign an item in a list box to a variable at a specific index with a loop with Option Strict On. its givin me the error "Option Strict On Disallows Late Binding." Error is at strSelected = lstCart.SelectedItem(index).ToString()
The loop basically needs to take each item in the list box, remove the first 20 characters(the name) and then trim the rest(the result is a price), then convert it to an integer using tryparse, then add it to the subtotal. After the program does this it displays the price in lblSub.Text
Option Strict On
Option Explicit On
Option Infer Off
Public Class Form1
Dim dblSubTotal As Double
Dim dblPrices() As Double = {4.99, 2.49, 6.49, 5.99, 11.99, 8.99, 4.49, 6.99, 0.99, 2.99}
Dim dblShipping As Double
Const SALES_TAX As Double = 0.04
Dim dblTax As Double
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
lstCds.Items.Add(("GardenKnomez").PadRight(20) & "- Across The Lawn")
lstCds.Items.Add(("The Pastries").PadRight(20) & "- Escape The Police")
lstCds.Items.Add(("Road Wasp").PadRight(20) & "- B Flat")
lstCds.Items.Add(("Paper Plated").PadRight(20) & "- Just Throw Us Away")
lstCds.Items.Add(("Exploding Bunions").PadRight(20) & "- Walk It Off")
lstCds.Items.Add(("NeverFart").PadRight(20) & "- Be Careful What You Wish For")
lstCds.Items.Add(("Hoth").PadRight(20) & "- In Michigan")
lstCds.Items.Add(("Naked Nation").PadRight(20) & "- Mabe SomeDay")
lstCds.Items.Add(("Poopsa").PadRight(20) & "- Pizza")
lstCds.Items.Add(("Hidden Valley").PadRight(20) & "- It's Only Ranch")
lstCds.SelectedIndex = 0
End Sub
Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
Dim strArtist As String
Dim intIndexSelected As Integer = lstCds.SelectedIndex
If lstCds.SelectedIndex = -1 Then
MessageBox.Show("Please make a selection... preferably Exploding Bunions")
Else
strArtist = lstCds.SelectedItem.ToString
strArtist = strArtist.Remove(20)
strArtist = strArtist.Trim()
lstCart.Items.Add((strArtist).PadRight(20) & dblPrices(intIndexSelected).ToString("C2"))
'Display Sub Total
dblSubTotal += dblPrices(intIndexSelected)
lblSub.Text = dblSubTotal.ToString("C2")
'Display Tax
dblTax = dblSubTotal * SALES_TAX
lblTax.Text = dblTax.ToString("C2")
'Display Shipping
If lstCart.Items.Count >= 5 Then
dblShipping = 5
ElseIf lstCart.Items.Count > 0 AndAlso lstCart.Items.Count < 5 Then
dblShipping = lstCart.Items.Count
End If
lblShipping.Text = dblShipping.ToString("C2")
'Display Total
lblTotal.Text = (dblSubTotal + dblTax + dblShipping).ToString("C2")
lstCds.SelectedIndex = -1
lstCart.SelectedIndex = lstCart.Items.Count - 1
End If
End Sub
Private Sub btnRemove_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
Dim intIndex As Integer
If lstCart.Items.Count = 0 Then
MessageBox.Show("Theres absolutely nothing in your cart, if you want to exit" &
" click ""FILE"" then click ""Exit""", "Discount Bin",
MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
ElseIf lstCart.SelectedIndex = -1 Then
MessageBox.Show("Are you ok? You have nothing selected in your cart.", "Discount Bin",
MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
lstCart.Items.RemoveAt(lstCart.SelectedIndex)
lstCds.SelectedIndex = 0
'subtract removed from subtotal
intIndex = lstCart.Items.Count - 1
dblSubTotal = 0
Dim strSelected As String
Dim dblSelected As Double
For index As Integer = 0 To intIndex
strSelected = lstCart.SelectedItem(index).ToString()
strSelected.Remove(0, 20)
strSelected.Trim()
Double.TryParse(strSelected, dblSelected)
dblSubTotal += dblSelected
Next index
lblSub.Text = dblSubTotal.ToString("C2")
'subtract removed from tax
End If
End Sub
Private Sub mnuFileExit_Click(sender As Object, e As EventArgs) Handles mnuFileExit.Click
If lstCart.Items.Count > 0 Then
Dim strPrice As String = lstCart.SelectedItem.ToString
strPrice = strPrice.Remove(0, 20)
strPrice = strPrice.Trim
strPrice.Insert(0, "$"c)
MessageBox.Show("We hope you enjoy your cd's because they're all pretty terrible," &
" especally the one for " & strPrice)
Else
MessageBox.Show("YOU'LL THANK YOURSELF LATER")
End If
Application.Exit()
End Sub
Private Sub mnuFileSave_Click(sender As Object, e As EventArgs) Handles mnuFileSave.Click
Dim outFile As IO.StreamWriter
If lstCart.Items.Count = 0 Then
MessageBox.Show("You dont have any items in your cart lol", "Discount Bin",
MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
Else
outFile = IO.File.CreateText("ThoseCdsYouWishYouNeverBought.txt")
For index As Integer = 1 To lstCart.Items.Count
lstCart.SelectedIndex = index - 1
outFile.WriteLine(lstCart.SelectedItem)
Next
MessageBox.Show("Reciept printed to your bin directory, your gunna need that.", "Discount Bin",
MessageBoxButtons.OK, MessageBoxIcon.Information)
outFile.Close()
Dim result As DialogResult = MessageBox.Show("Do you want to keep shopping?", "Discount Bin",
MessageBoxButtons.YesNo, MessageBoxIcon.Question)
If result = DialogResult.No Then
Application.Exit()
End If
End If
End Sub
Private Sub lstCart_MouseDown(sender As Object, e As MouseEventArgs) Handles lstCart.MouseDown
lstCds.SelectedIndex = -1
End Sub
End Class

Answer 1

this is incorrect:
Dim strSelected As String
For index As Integer = 0 To intIndex
strSelected = lstCart.SelectedItem(index).ToString()
Next index
lblSub.Text = dblSubTotal.ToString("C2")
SelectedItem is a single object, so you cant index it. to loop thru the SelectedItemS:
Dim n As Integer = 0 to lstCart.SelectedItems.Count - 1
strSelected = lstCart.SelectedItems(n)
' this is pointless because you do nothing with it
Next n
You can put class objects in the listbox, in which case when getting them back you need to convert/cast the Item object back to the correct Type (this is usually the case with that error message):
strName = CType(lstCart.SelectedItem, ItemClass).PropertyName
this would convert an object stored as the SelectedItem back to the Class type, so its props can be referenced. your code is a perfect candicate for a class - it would keep the name and price together rather than having to look things up in other arrays. As soon as you sort the listbox, the indicies no longer match and Gnomes points to the price for Garden Weasel
Edit
To remove the selected items:
For n as Integer = lstCart.SelectedItems.Count - 1 To 0 Step -1
' MUST loop backwards
lstCart.Items.Remove(lstCart.SelectedItems(n)
Next n
after the purge, reloop to recalc instead of subtracting.