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  1. #1
    Join Date
    Dec 2008
    Posts
    13

    Post exception errors

    I am beginning to use exceptions in visual basic and haveing issues with my compute button(totals button works fine). My issue is I have a group box of customer information and the customer name, shipping address, and telephone cannot be blank and just need help on how I can throw exception with this. I also have a purchase information group box that checks to make sure product identifier, purchase price, and quantity purchased are not blank either. I was able to get this to work fine for purchase price and quantity purchased but does not work for product identifier. If someone could please walk me through this so I hopefully wont have to ask how to do exceptions again. Here is my code and if I need to explain anything better please let me know...

    Code:
    Public Class Form1
    
        'Declare module level variables
        Private totalDiscountDecimal As Decimal
        Private totalQuantityInteger As Integer
    
        Private Sub computeButton_Click(sender As Object, e As EventArgs) Handles computeButton.Click
            'Begin try statement to check for errors
            Try
    
                'Declare constant for sales tax
                Const SALES_TAX As Single = 0.05
                Const FED_EX_AIR As Single = 25.0
                Const FED_EX_GROUND As Single = 20.0
                Const US_POSTAL As Single = 12.0
                Const ONE_YEAR_WARRANTY As Single = 75.0
                Const CLUB_MEMBERSHIP As Single = 150.0
                Const TIRE_SALE As Single = 25.0
                Const WHOLESALE_DISCOUNT As Single = 0.1
                Const RETAIL_DISCOUNT As Single = 0.0
    
                'Declare variables
                Dim subtotalDecimal, totalDueDecimal, salesTaxDecimal, shippingCostDecimal, oneYearWarrantyDecimal,
                extrasDecimal, clubMembershipDecimal, tireSaleDecimal, discountDecimal As Decimal
    
    
                'Declare variables and convert values from textbox controls to memory
                Dim purchasePriceDecimal As Decimal = Decimal.Parse(purchasePriceTextBox.Text, Globalization.NumberStyles.Currency)
                Dim quantityPurchasedInteger As Integer = Integer.Parse(quantityPurchasedTextBox.Text, Globalization.NumberStyles.Number)
    
    
                'Determine the shipping cost if fed ex air is clicked
                If fedExAirRadioButton.Enabled Then
                    shippingCostDecimal = FED_EX_AIR
                ElseIf fedExGroundRadioButton.Enabled Then
                    shippingCostDecimal = FED_EX_GROUND
                ElseIf USPostalRadioButton.Enabled Then
                    shippingCostDecimal = US_POSTAL
                End If
    
                'Calculate total shipping cost
                shippingCostDecimal *= quantityPurchasedInteger
    
                'Show the results in a textbox
                shippingCostTextBox.Text = shippingCostDecimal
    
                'Check extras
                If oneYearWarrantyCheckBox.Checked Then
                    oneYearWarrantyDecimal = ONE_YEAR_WARRANTY
                End If
                If clubMembershipCheckBox.Checked Then
                    clubMembershipDecimal = CLUB_MEMBERSHIP
                End If
                If tireSaleCheckBox.Checked Then
                    tireSaleDecimal = TIRE_SALE
                End If
    
                'Determine extrasDecimal
                extrasDecimal = oneYearWarrantyDecimal + clubMembershipDecimal + tireSaleDecimal
    
                'Determine the discount
                If wholesaleRadioButton.Checked Then
                    discountDecimal = (purchasePriceDecimal * quantityPurchasedInteger) * WHOLESALE_DISCOUNT
    
                ElseIf retailRadioButton.Checked Then
                    discountDecimal = RETAIL_DISCOUNT
                End If
    
                subtotalDecimal = purchasePriceDecimal * quantityPurchasedInteger + shippingCostDecimal + extrasDecimal - discountDecimal
    
                'Determine the sales tax
                If wholesaleRadioButton.Checked Then
                    salesTaxDecimal = 0.0
                ElseIf retailRadioButton.Checked Then
                    salesTaxDecimal = subtotalDecimal * SALES_TAX
                End If
    
                'Determine the total due
                totalDueDecimal = subtotalDecimal + salesTaxDecimal
    
    
                'Display output in textboxes
                salesTaxTextBox.Text = salesTaxDecimal.ToString("C")
                subtotalTextBox.Text = subtotalDecimal.ToString("C")
                shippingCostTextBox.Text = shippingCostDecimal.ToString("C")
                costOfExtrasTextBox.Text = extrasDecimal.ToString("C")
                discountTextBox.Text = discountDecimal.ToString("C")
                totalDueTextBox.Text = totalDueDecimal.ToString("C")
    
    
                'Enable\Disable buttons
                computeButton.Enabled = False
                resetButton.Enabled = True
    
                'Accumulate totals
                totalDiscountDecimal += discountDecimal
                totalQuantityInteger += quantityPurchasedInteger
    
            Catch ex As Exception
                MessageBox.Show("Product identifier, purchase price, or quantity purchased has not been entered!",
                                "Customer name error", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try
    
        End Sub
    
        Private Sub totalCountAverageButton_Click(sender As Object, e As EventArgs) Handles totalCountAverageButton.Click
            'Try statement to check for errors
            Try
                'Determine the average Discount
                Dim averageDiscountDecimal = totalDiscountDecimal / totalQuantityInteger
    
                'Display totals in a message string
                Dim messageString As String = "Total Wholesale Discounts: " & totalDiscountDecimal.ToString("C") &
                                            ControlChars.NewLine & "Total Wholesale Quantity Sold: " & totalQuantityInteger.ToString("N0") &
                                            ControlChars.NewLine & "Average Discount Amount: " & averageDiscountDecimal.ToString("C")
    
                'Display a header for the message string
                MessageBox.Show(messageString, "Totals, Counts and Averages", MessageBoxButtons.OK, MessageBoxIcon.Information)
    
            Catch exArithmeticException As ArithmeticException
                MessageBox.Show("No products have been sold yet", "Zero Sales Message", MessageBoxButtons.OK, MessageBoxIcon.Information)
    
            Catch ex As Exception
                MessageBox.Show("Unexpected error - inform the system administrator", "Unknown error in totals",
                                MessageBoxButtons.OK, MessageBoxIcon.Error)
    
            End Try
        End Sub
    
        Private Sub resetButton_Click(sender As Object, e As EventArgs) Handles resetButton.Click
            'Clear the textboxes
            customerNameTextBox.Clear()
            shippingAddressTextBox.Clear()
            telephoneMaskedTextBox.Clear()
            productIdentifierTextBox.Clear()
            purchasePriceTextBox.Clear()
            quantityPurchasedTextBox.Clear()
            shippingCostTextBox.Clear()
            costOfExtrasTextBox.Clear()
            discountTextBox.Clear()
            subtotalTextBox.Clear()
            salesTaxTextBox.Clear()
            totalDueTextBox.Clear()
    
            'Set radio buttons back to default
            wholesaleRadioButton.Checked = True
            fedExAirRadioButton.Checked = True
    
            'Uncheck all the extras checkboxes
            oneYearWarrantyCheckBox.Checked = False
            clubMembershipCheckBox.Checked = False
            tireSaleCheckBox.Checked = False
    
            'Set the focus to the customer name textbox
            customerNameTextBox.Focus()
    
            'Enable\disable buttons
            computeButton.Enabled = True
            resetButton.Enabled = False
        End Sub
    
        Private Sub exitButton_Click(sender As Object, e As EventArgs) Handles exitButton.Click
            'Exit the program with being prompted to exit
            Dim response As Integer
            response = MessageBox.Show("Do you want to close the form?", "Quit?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2)
    
            If response = vbYes Then
                Me.Close()
            End If
        End Sub
    
    End Class

  2. #2
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,951

    Re: exception errors

    You don't need to use EXCEPTION HANDLING for that. That is more for system errors, not program errors. Just check if the field(s) are BLANK or NOTHING, and set a flag for each one. Set it FALSE before the checks, and if there is ANY error, each one can set it to TRUE. Check for TRUE before executing the code which might cause the exception. Of course, if there is any chance of a missing CD or Network Share, then, use and EXCEPTION. ON ERROR XXX

    Here's a quick sample:

    Code:
    Public Function DigestFileToHS(InFile As String) As String
    On Error GoTo errorhandler
    GoSub begin
    
    errorhandler:
        DigestFileToHexStr = ""
        Exit Function
        
    begin:
        Dim FileO As Integer
        FileO = FreeFile
        Call FileLen(InFile)
        Open InFile For Binary Access Read As #FileO
        MD5Init
        Do While Not EOF(FileO)
            Get #FileO, , ByteBuffer
            If Loc(FileO) < LOF(FileO) Then
                ByteCounter = ByteCounter + 64
                MD5Transform ByteBuffer
            End If
        Loop
        ByteCounter = ByteCounter + (LOF(FileO) Mod 64)
        Close #FileO
        MD5Final
        DigestFileToHS = GetValues
    End Function
    David

    CodeGuru Article: Bound Controls are Evil-VB6
    2013 Samples: MS CODE Samples

    CodeGuru Reviewer
    2006 Dell CSP
    2006, 2007 & 2008 MVP Visual Basic
    If your question has been answered satisfactorily, and it has been helpful, then, please, Rate this Post!

  3. #3
    Join Date
    Dec 2008
    Posts
    13

    Post Re: exception errors

    I am only in chapter 4 on this visual basic book so the code below is way over my head as this stage lol.

    I kind of messed around with it alittle and I do get an error to come up now with the code below but the only issue is aftern the error does come up the program still computer the totals...

    Code:
    Public Class Form1
    
        'Declare module level variables
        Private totalDiscountDecimal As Decimal
        Private totalQuantityInteger As Integer
    
        Private Sub computeButton_Click(sender As Object, e As EventArgs) Handles computeButton.Click
            'Begin try statement to check for errors
            Try
    
                'Declare constant for sales tax
                Const SALES_TAX As Single = 0.05
                Const FED_EX_AIR As Single = 25.0
                Const FED_EX_GROUND As Single = 20.0
                Const US_POSTAL As Single = 12.0
                Const ONE_YEAR_WARRANTY As Single = 75.0
                Const CLUB_MEMBERSHIP As Single = 150.0
                Const TIRE_SALE As Single = 25.0
                Const WHOLESALE_DISCOUNT As Single = 0.1
                Const RETAIL_DISCOUNT As Single = 0.0
    
                'Declare variables
                Dim subtotalDecimal, totalDueDecimal, salesTaxDecimal, shippingCostDecimal, oneYearWarrantyDecimal,
                extrasDecimal, clubMembershipDecimal, tireSaleDecimal, discountDecimal As Decimal
    
    
                'Declare variables and convert values from textbox controls to memory
                Dim purchasePriceDecimal As Decimal = Decimal.Parse(purchasePriceTextBox.Text, Globalization.NumberStyles.Currency)
                Dim quantityPurchasedInteger As Integer = Integer.Parse(quantityPurchasedTextBox.Text, Globalization.NumberStyles.Number)
    
                If customerNameTextBox.Text = String.Empty Then
                    MessageBox.Show("Customer name cannot be blank", "Customer name error",
                                MessageBoxButtons.OK, MessageBoxIcon.Error)
                    customerNameTextBox.Focus()
                End If
    
                If shippingAddressTextBox.Text = String.Empty Then
                    MessageBox.Show("Shipping address cannot be blank", "Shipping address error",
                                MessageBoxButtons.OK, MessageBoxIcon.Error)
                    customerNameTextBox.Focus()
                End If
    
                If telephoneMaskedTextBox.Text = String.Empty Then
                    MessageBox.Show("Phone number cannot be blank", "Telephone error",
                                MessageBoxButtons.OK, MessageBoxIcon.Error)
                    customerNameTextBox.Focus()
                End If
                'Determine the shipping cost if fed ex air is clicked
                If fedExAirRadioButton.Enabled Then
                    shippingCostDecimal = FED_EX_AIR
                ElseIf fedExGroundRadioButton.Enabled Then
                    shippingCostDecimal = FED_EX_GROUND
                ElseIf USPostalRadioButton.Enabled Then
                    shippingCostDecimal = US_POSTAL
                End If
    
                'Calculate total shipping cost
                shippingCostDecimal *= quantityPurchasedInteger
    
                'Show the results in a textbox
                shippingCostTextBox.Text = shippingCostDecimal
    
                'Check extras
                If oneYearWarrantyCheckBox.Checked Then
                    oneYearWarrantyDecimal = ONE_YEAR_WARRANTY
                End If
                If clubMembershipCheckBox.Checked Then
                    clubMembershipDecimal = CLUB_MEMBERSHIP
                End If
                If tireSaleCheckBox.Checked Then
                    tireSaleDecimal = TIRE_SALE
                End If
    
                'Determine extrasDecimal
                extrasDecimal = oneYearWarrantyDecimal + clubMembershipDecimal + tireSaleDecimal
    
                'Determine the discount
                If wholesaleRadioButton.Checked Then
                    discountDecimal = (purchasePriceDecimal * quantityPurchasedInteger) * WHOLESALE_DISCOUNT
    
                ElseIf retailRadioButton.Checked Then
                    discountDecimal = RETAIL_DISCOUNT
                End If
    
                subtotalDecimal = purchasePriceDecimal * quantityPurchasedInteger + shippingCostDecimal + extrasDecimal - discountDecimal
    
                'Determine the sales tax
                If wholesaleRadioButton.Checked Then
                    salesTaxDecimal = 0.0
                ElseIf retailRadioButton.Checked Then
                    salesTaxDecimal = subtotalDecimal * SALES_TAX
                End If
    
                'Determine the total due
                totalDueDecimal = subtotalDecimal + salesTaxDecimal
    
    
                'Display output in textboxes
                salesTaxTextBox.Text = salesTaxDecimal.ToString("C")
                subtotalTextBox.Text = subtotalDecimal.ToString("C")
                shippingCostTextBox.Text = shippingCostDecimal.ToString("C")
                costOfExtrasTextBox.Text = extrasDecimal.ToString("C")
                discountTextBox.Text = discountDecimal.ToString("C")
                totalDueTextBox.Text = totalDueDecimal.ToString("C")
    
    
                'Enable\Disable buttons
                computeButton.Enabled = False
                resetButton.Enabled = True
    
                'Accumulate totals
                totalDiscountDecimal += discountDecimal
                totalQuantityInteger += quantityPurchasedInteger
    
            Catch ex As Exception
                MessageBox.Show("Product identifier, purchase price, or quantity purchased has not been entered!",
                                "Customer name error", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try
    
        End Sub
    
        Private Sub totalCountAverageButton_Click(sender As Object, e As EventArgs) Handles totalCountAverageButton.Click
            'Try statement to check for errors
            Try
                'Determine the average Discount
                Dim averageDiscountDecimal = totalDiscountDecimal / totalQuantityInteger
    
                'Display totals in a message string
                Dim messageString As String = "Total Wholesale Discounts: " & totalDiscountDecimal.ToString("C") &
                                            ControlChars.NewLine & "Total Wholesale Quantity Sold: " & totalQuantityInteger.ToString("N0") &
                                            ControlChars.NewLine & "Average Discount Amount: " & averageDiscountDecimal.ToString("C")
    
                'Display a header for the message string
                MessageBox.Show(messageString, "Totals, Counts and Averages", MessageBoxButtons.OK, MessageBoxIcon.Information)
    
            Catch exArithmeticException As ArithmeticException
                MessageBox.Show("No products have been sold yet", "Zero Sales Message", MessageBoxButtons.OK, MessageBoxIcon.Information)
    
            Catch ex As Exception
                MessageBox.Show("Unexpected error - inform the system administrator", "Unknown error in totals",
                                MessageBoxButtons.OK, MessageBoxIcon.Error)
    
            End Try
        End Sub
    
        Private Sub resetButton_Click(sender As Object, e As EventArgs) Handles resetButton.Click
            'Clear the textboxes
            customerNameTextBox.Clear()
            shippingAddressTextBox.Clear()
            telephoneMaskedTextBox.Clear()
            productIdentifierTextBox.Clear()
            purchasePriceTextBox.Clear()
            quantityPurchasedTextBox.Clear()
            shippingCostTextBox.Clear()
            costOfExtrasTextBox.Clear()
            discountTextBox.Clear()
            subtotalTextBox.Clear()
            salesTaxTextBox.Clear()
            totalDueTextBox.Clear()
    
            'Set radio buttons back to default
            wholesaleRadioButton.Checked = True
            fedExAirRadioButton.Checked = True
    
            'Uncheck all the extras checkboxes
            oneYearWarrantyCheckBox.Checked = False
            clubMembershipCheckBox.Checked = False
            tireSaleCheckBox.Checked = False
    
            'Set the focus to the customer name textbox
            customerNameTextBox.Focus()
    
            'Enable\disable buttons
            computeButton.Enabled = True
            resetButton.Enabled = False
        End Sub
    
        Private Sub exitButton_Click(sender As Object, e As EventArgs) Handles exitButton.Click
            'Exit the program with being prompted to exit
            Dim response As Integer
            response = MessageBox.Show("Do you want to close the form?", "Quit?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2)
    
            If response = vbYes Then
                Me.Close()
            End If
        End Sub
    
    End Class

  4. #4
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,951

    Re: exception errors

    Print out the values as the error occurs.

    Code:
    Catch ex As Exception
                MessageBox.Show("Product identifier, purchase price, or quantity purchased has not been entered!",
                ' Debug.Print         x & vbCrLf & y  & vbCrLf & z
    It should help identify the error. You can use an ON ERROR statement, with the TRY/CATCH
    David

    CodeGuru Article: Bound Controls are Evil-VB6
    2013 Samples: MS CODE Samples

    CodeGuru Reviewer
    2006 Dell CSP
    2006, 2007 & 2008 MVP Visual Basic
    If your question has been answered satisfactorily, and it has been helpful, then, please, Rate this Post!

  5. #5
    Join Date
    Dec 2001
    Posts
    6,332

    Re: exception errors

    Doesn't look quite like classic VB6 to me. is this .net you're working with by any chance?
    Please remember to rate the posts and threads that you find useful.
    How can something be both new and improved at the same time?

  6. #6
    Join Date
    Dec 2008
    Posts
    13

    Post Re: exception errors

    I used your advice and added a messagebox to check each textbox and worked great with the exception of the masked textbox. I am guessing since there are '(', ')', and '-' already in the textbox that I will need to use a different way of checking to make sure all 10 digits are entered. All i found was the following code which did not work

    If telephoneTextbox.Text = nothing then

    Here is the code which I have shortened up....

    Code:
               'Declare Dim statements to check for errors
                Dim customerNameError As New System.Text.StringBuilder
                Dim shippingAddressNameError As New System.Text.StringBuilder
                Dim telephoneError As New System.Text.StringBuilder
                Dim productIdentifierError As New System.Text.StringBuilder
    
                'If statement to check if customer name is blank
                If String.IsNullOrWhiteSpace(customerNameTextBox.Text) Then
                    customerNameError.AppendLine("Name required")
                    customerNameTextBox.Focus()
                End If
    
                'Message box for error in customer name
                If customerNameError.ToString.Length > 0 Then
                    MessageBox.Show(customerNameError.ToString, "Error in Customer Information", MessageBoxButtons.OK, MessageBoxIcon.Error)
                    Exit Sub
                End If
    
                'If statement to check if shipping address is blank
                If String.IsNullOrWhiteSpace(shippingAddressTextBox.Text) Then
                    shippingAddressNameError.AppendLine("Shipping address required")
                    shippingAddressTextBox.Focus()
                End If
    
                'Message box for error in shipping address
                If shippingAddressNameError.ToString.Length > 0 Then
                    MessageBox.Show(shippingAddressNameError.ToString, "Error in Shipping Information", MessageBoxButtons.OK, MessageBoxIcon.Error)
                    Exit Sub
                End If
    
                'If statement to check if telephone number is valid
                If String.IsNullOrWhiteSpace(telephoneMaskedTextBox.Text) Then
                    telephoneError.AppendLine("Telephone required")
                End If
    
                'Message box for error in telephone number
                If telephoneError.ToString.Length < 0 Then
                    MessageBox.Show(customerNameError.ToString, "Error in Telephone Number", MessageBoxButtons.OK, MessageBoxIcon.Error)
                    Exit Sub
                End If
    
                'If statement to check if product identifier is blank
                If String.IsNullOrWhiteSpace(productIdentifierTextBox.Text) Then
                    productIdentifierError.AppendLine("Product Identifier required")
                    productIdentifierTextBox.Focus()
                End If
    
                'Messagebox for error in product identifier
                If productIdentifierError.ToString.Length < 0 Then
                    MessageBox.Show(productIdentifierError.ToString, "Errors in Purchase Information", MessageBoxButtons.OK, MessageBoxIcon.Error)
                    Exit Sub
                End If

  7. #7
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,951

    Re: exception errors

    Use a HIDDEN textbox for the MASKED TB. Let user type into normal textbox, check it, and then show the MTB with the value
    David

    CodeGuru Article: Bound Controls are Evil-VB6
    2013 Samples: MS CODE Samples

    CodeGuru Reviewer
    2006 Dell CSP
    2006, 2007 & 2008 MVP Visual Basic
    If your question has been answered satisfactorily, and it has been helpful, then, please, Rate this Post!

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