Move textbox price to Subtotal (and add)

Question

Hello All I'm an e-student at a local college just learning the art of programming for the first time. For the most I’ve been able to muddle through the course using the books and without asking any questions. When I finally posed one the instructors answer was to say the lest mystifying. With the hopes of getting a real answer I’ve decided to post my question here. I am writing a relatively simple Sales Receipt program in VB.net with one “add to the list” button a textbox to type in the “price” a listbox to keep track of the numbers I’ve entered and three more textboxes to tally the sub tax and total. I’ve managed to accomplish the basic task of getting the textbox “price” into the listbox and maintaining the cursor focus on the textbox. I know how to calculate the sub tax and total. But I can’t seem to wrap my head around the “ How do I get the listbox accumulated into the subtotal textbox ?” A code that will add up the items in the list as they accumulate is not feasible. What I need I something a beginner can accomplish like taking the textbox “price” and add it not only to the listbox as ive done but also place it into the Subtotal textbox . Then with each additional price keep up with the addition. Can it be done? Here is my code so far Private Sub Form1_Load( ByVal sender As Object  ByVal e As System.EventArgs) Handles MyBase .Load Dim TextBox1 As Double Dim ListBox1 As Double Dim txtSubtotal As Double Dim txtTax As Double Dim txtTotal As Double End Sub Private Sub BtnAdd_Click( ByVal sender As System.Object ByVal e As System.EventArgs) Handles BtnAdd.Click 'Clear and Retain TextBox1 Focus Dim Source As String Source = TextBox1.Text TextBox1.Text = ListBox1.Items.Add(Source) If TextBox1.TextLength = 0 Then TextBox1.Focus() End If If ListBox1.Items.Contains(Source) = True Then TextBox1.Clear() TextBox1.Focus() End If 'Calculate amounts Dim SubTotal As Decimal Dim CurrentTaxRate As Decimal Dim Tax As Decimal Dim TotalDue As Decimal txtSubTotal.Text = SubTotal CurrentTaxRate = 0.065 Tax = CDec (SubTotal * (CurrentTaxRate)) txtTax.Text = (Tax) TotalDue = (SubTotal + (Tax)) txtTotal.Text = (TotalDue) End Sub 'Format Sales Receipt as currency Private Sub TextBox1_Leave( ByVal sender As Object  ByVal e As System.EventArgs) Handles TextBox1.Leave TextBox1.Text = FormatCurrency(TextBox1.Text) End Sub End Class Someplace in there I need a running Subtotal for this to work. I hate to ask questions but I'm overlooking somthing and I need help. Thanks for your time H~

Howard · Answer

Brilliant! There I was thinking I needed that IF statement and as a student how smart I was for using it. It was the First time I’d ever written an If Statement so I guess I stubbornly overlooked that obvious flaw in my program. Lesson Learned. Thank You Ezdehar you have been extremely helpful. PS. I do have another If statement in the program that works just fine. It insures that only numbers are placed in the TextBox. It works. :)

Ezdehar Noor · Answer

Hi i can not understand the purpose of this if why u write it If ListBox1.Items.Contains(Source) = True Then i tried the following code in a test project and it achieve the things u need (if i understood u correctly) without exceptions Private Sub addbtn_Click( ByVal sender As System.Object ByVal e As System.EventArgs) Handles addbtn.Click Dim Source As String Source = TextBox1.Text TextBox1.Text = ListBox1.Items.Add(Source) TextBox1.Clear() TextBox1.Focus() End Sub Private Sub ext_Click( ByVal sender As System.Object ByVal e As System.EventArgs) Handles ext.Click End End Sub if there is misunderstaning tell me pls

Howard · Answer

OK it me again It's hot the work is pitilessly agonizing and now I’m all tangled up. Yet I’m | this | close to completion. Can I ask just one more question? I know my problem lies in the Focus that I’ve placed on the textbox but it sort of needs it to be like this. Privet Sub BtnAdd_Click ( bla bla bla) Dim Source As String Source = TextBox1.Text TextBox1.Text = ListBox1.Items.Add(Source) If ListBox1.Items.Contains(Source) = True Then TextBox1.Clear() TextBox1.Focus() End If Otherwise I’d have to mouse click back to the textbox and backspace as it counts up form zero without the clear and focus commands in place. However as written with the focus concentrated on the textbox  I’m unable to exit using the BtnExit_click command. Is there some way I can If and Else my way out of this predicament. Or place some override or redirect focus on the Exit button. What I real don’t understand is…Why doesn’t my exit button work but my add button does? A button click by definition should place the focus on the click.

Howard · Answer

In the immortal words of Elvis “Thank You thank you very much”. I had to tweak my code just a little to make it work for me but as a work in progress I have some extra code in places which I do not need and have to remove it anyway - so tweaking is all part of the clean up process. But yes your solution worked great. I wrote it down in my note book under “Ezdehar’s solution” in case I come across another problem like it. Thanks again. I’m now just trying to figure out where I went wrong with retaining focus on textbox1. I believe now when I click exit (BtnExit_Click) I get an unhandled exception error because of it. I Think maybe I need another If condition statment in there.

Ezdehar Noor · Answer

Hello I think that your problem is simple (if i understood it correctly) to accumulate the subtotal textbox with the total prices you can write Dim i As Integer Dim tot As Decimal = 0 For i = 0 To Me.ListBox1.Items.Count - 1 tot += Me.ListBox1.Items(i) Next SubTotal.Text = tot if there is misunderstanding pls tell me (usually humans aske when they dont know some thing  question is a good method to benifits from other experiences)

Move textbox "price" to Subtotal (and add)