Unhandled Expections?!?!

T

thankins

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Sep 24, 2003
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I recieve the following message when i try to compile my program, and I dont know what it means!

An unhandled exception of type 'System.InvalidCastException' occurred in microsoft.visualbasic.dll

Additional information: Cast from string "10%" to type 'Single' is not valid.
Click to expand...

I am trying to make it so when the user enters a number with the percent sign (10%) into my text box the program will treat it like 10.0

Here are parts of my code

Code: 
    Private Sub txtFederal_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtFederal.Validating
        'Vaildates that a number has been entered into the text box

        If Not IsNumeric(Val(txtFederal.Text)) Then
            MessageBox.Show("Federal taxes must be a number.", "Invaild Input", MessageBoxButtons.OK, _
            MessageBoxIcon.Error)

            'Select the existing text in the text box.
            txtFederal.SelectionStart = 0
            txtFederal.SelectionLength = txtFederal.Text.Length
            'Set the e.Cacel to true so the focus will stay in the control
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub

and here is the part where the error is occuring
Code: 
    Sub InputData(ByRef empName As String, ByRef hrRate As Single, ByRef hrsWorked As Single, ByRef fedTax As Single, ByRef ficaTax As Single, ByRef stateTax As Single)

        ' Get payroll data for employee
        empName = txtName.Text
        hrRate = CInt(txtRate.Text)
        hrsWorked = CInt(txtHours.Text)
       [COLOR=blue]fedTax = CSng(txtFederal.Text)[/COLOR] 
        ficaTax = CSng(txtFica.Text)
        stateTax = CSng(txtState.Text)

The bluw text above is where the error is occuring
 
You need to strip off the % in order for it to parse the number correctly. For example:
Visual Basic: 
fedTax = Single.Parse(txtFederal.Text.SubString(0, txtFederal.Text.Length - 1)
 
What exact is the single.parse command? I looked in my vb . net book and didnt see anything. Do you mind explaining it
 
I put it into my code and now i recieve a new error

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll

Additional information: Input string was not in a correct format.
Click to expand...

I copied it from what was posted

Code: 
   fedTax = Single.Parse(txtFederal.Text.Substring(0, txtFederal.Text.Length - 1))
 
Right before that line, put this:
Visual Basic: 
MessageBox.Show(txtFederal.Text.SubString(0, txtFederal.Text.Length - 1))
and post here what it says.
 
But I thought you wanted to be able to enter in a % sign? Try this, then:
Visual Basic: 
If txtFederal.Text.EndsWith("%") Then fedTax = Single.Parse(txtFederal.Text.Substring(0, txtFederal.Text.Length - 1))
The problem is that it's removing the last character (which I assumed would be a %). If it's not always going to be % you need to check, which is what my code above does.
 
Yes I do, but I want to have a way so that if the user doesnt enters the percent sign the program won't crash, so i should use the if statement then correct?!

Also while we are on the topic of percent, how would you go about turning the number they enter into a percent? Because now how I have the program set up it just treats it as a whole number

Code: 
  Function Fed_Tax(ByRef grossPay As Single, ByRef fedTax As Single) As Single
        'Compute amount to be taken for Federal Tax
        Fed_Tax = grossPay * fedTax

I thought about adding a ".01 to the fed tax so that it reads

Code: 
   Function Fed_Tax(ByRef grossPay As Single, ByRef fedTax As Single) As Single
        'Compute amount to be taken for Federal Tax
        Fed_Tax = grossPay * (fedTax * .01)

But i didnt know if that was "good programming" or not.
 
1) Yes, the code in my previous post will allow you to put a percent sign or not put one. You may even want to trim it so no extra spaces will throw it off:
Visual Basic: 
Dim sTax As String = txtFederal.Text.Trim() 'added the variable for cleanliness, and the Trim() 
                                            'call to remove any spaces that are padding the number.

fedTax = Single.Parse(sTax.Substring(0, sTax.Length - 1))

2) Yes, that's the way you do it.
 
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