loop through list box in vb and get a total amount - vb.net

Question

I’m trying to loop through a list of prices on a list box and print the total in a textbox on the form. The loop I have works, but the figures it produces are all wrong!. can any one help me??
the figures look ok but then when i add more items to the list box the total amount goes all wrong.
Public Class f
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'LoftDataSet.Services' table. You can move, or remove it, as needed.
Me.ServicesTableAdapter.Fill(Me.LoftDataSet.Services)
'Loop through all the rows that are in the dataset
For Each dr As DataRow In LoftDataSet.Services.Rows
Dim btn As New Button 'Instantiate a button
btn.Text = dr("service_name").ToString 'UserName is a field in my Users Table
btn.Size = New Size(140, 80)
btn.Tag = dr("ID") 'Here we set the tag to the primary key (ID)
'Since we're using a flowlayoutpanel, we don't need to worry about setting the location property
FlowLayoutPanel1.Controls.Add(btn) 'Add the button to the flow layout panel
AddHandler btn.Click, AddressOf UserClick 'Here we give the button a handler for the click event
Next
End Sub
Public Class Product
Public Property ProductName As String
Public Property ProductCost As Decimal
Public Overrides Function ToString() As String
Return ProductCost & " " & ProductName
'Here you could build a formatted string to the user to include cost
End Function
End Class
'Here we write our method for the click event of the button(s) we created
Dim SelectedProduct As New Product
Private Sub UserClick(ByVal sender As Object, ByVal e As EventArgs)
'We set a filter to the binding source passing it ID=<and whatever is stored in the tag property>
ServicesBindingSource.Filter = "ID = " & DirectCast(sender, Button).Tag.ToString
SelectedProduct.ProductName = DirectCast(sender, Button).Text
SelectedProduct.ProductCost = DirectCast(ServicesBindingSource(0), DataRowView).DataView(0)(2)
ListBox1.Items.Add(SelectedProduct)
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
For i As Integer = ListBox1.SelectedIndices.Count - 1 To 0 Step -1
ListBox1.Items.RemoveAt(ListBox1.SelectedIndices(i))
Next
End Sub
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim aValue As Decimal
For Each item As Product In ListBox1.Items
aValue += CDec(item.ProductCost)
Next
TextBox1.Text = aValue
End Sub
End Class

Answer 1

Cycle through each item using an integer as your count.
For i As Integer = 0 To ListBox1.Items.Count - 1
MsgBox(ListBox1.Items(i).ToString)
Next
Or you can add it to an integer/double value
For i As Integer = 0 To ListBox1.Items.Count - 1
MyInteger += Double.Parse.ListBox1.Items(i).ToString)
Next
MsgBox(MyInteger)
'Now the messagebox will show your total
EDIT:
Do not use ListBo1.Items.Item(i). Access directly through Listbox1.Items(i)