need help with VB 08 Calculator

[jac130]

I need to create a calculator using combo boxes/procedures/functions etc... and some other stuff. most of it works properly, but, i need to create a user defined function that checks if both input numbers of the calculation are in fact numbers (isnumeric). the function must check both numbers, display a message box and return a value. but it crashes every time i test it - like putting in a letter instead of a number. any help would be great,
here's my code so far: (first function is the one malfunctioning)
Public Class form1
Function checknumber(ByV al num1 As String, ByVal num2 As String) As Boolean
If Not IsNumeric(num1) Then
MsgBox("Input must be a number.")
ElseIf Not IsNumeric(num2) Then
MsgBox("Input must be a number.")
Return False
End If

End Function
Sub rounding(ByVal roundnum As Double)
If txtRound.Enable d = True Then
txtResult.Text = FormatNumber(tx tResult.Text, roundnum)
End If
End Sub
Private Sub btnEquals_Click (ByVal sender As System.Object, ByVal e As System.EventArg s) Handles btnEquals.Click
Dim num1, num2, roundnum As Double
num1 = txtNum1.Text
num2 = txtNum2.Text
roundnum = txtRound.Text


If cmbOperation.Te xt = "Addition" Then
'calculate result
addition(num1, num2)
End If

If cmbOperation.Te xt = "Subtractio n" Then
'calculate result
subtraction(num 1, num2)
End If

If cmbOperation.Te xt = "Multiplication " Then
'calculate result
multiplication( num1, num2)
End If

If cmbOperation.Te xt = "Division" Then
'calculate result
division(num1, num2)
End If

If cmbOperation.Te xt = "Mod" Then
'calculate result
modular(num1, num2)
End If
If cmbOperation.Te xt = "Exponentiation " Then
'calculate result
exponentiate(nu m1, num2)
End If

'validate operation
If cmbOperation.Te xt = "" Then
MsgBox("no operation is selected.")
End If
End Sub


Sub addition(ByVal num1 As Double, ByVal num2 As Double)
checknumber(num 1, num2)
txtResult.Text = (num1 + num2)
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub

Sub subtraction(ByV al num1 As Double, ByVal num2 As Double)
txtResult.Text = num1 - num2
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub

Sub multiplication( ByVal num1 As Double, ByVal num2 As Double)
txtResult.Text = num1 * num2
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub

Sub division(ByVal num1 As Double, ByVal num2 As Integer)
'validate input
If num2 = 0 Then
MsgBox("Number 2 cannot be 0.")
Exit Sub
End If
txtResult.Text = num1 / num2
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub
Sub modular(ByVal num1 As Double, ByVal num2 As Double)
'validate input
If num2 = 0 Then
MsgBox("Number 2 cannot be 0.")
Exit Sub
End If
txtResult.Text = num1 Mod num2
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub
Sub exponentiate(By Val num1 As Double, ByVal num2 As Double)
'validate input
If num1 = 0 And num2 < 0 Then
MsgBox("input is invalid.")
Exit Sub
End If
txtResult.Text = num1 ^ num2
'build list
lstResults.Item s.Add(txtResult .Text)
End Sub
Private Sub btnClear_Click( ByVal sender As System.Object, ByVal e As System.EventArg s) Handles btnClear.Click
lstResults.Item s.Clear()
txtNum1.Text = ""
txtNum2.Text = ""
txtRound.Text = ""
txtResult.Text = ""
cmbOperation.Te xt = ""
radRound.Checke d = False
End Sub

Private Sub radRound_Checke dChanged(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles radRound.Checke dChanged
'disable rounding option unless user wants to round
If radRound.Checke d = True Then
'allow user to round
txtRound.Enable d = True
Else
'do not allow rounding
txtRound.Enable d = False
End If
End Sub

Private Sub lstResults_Sele ctedIndexChange d(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles lstResults.Sele ctedIndexChange d
If lstResults.Sele ctedIndex >= 0 Then
If MsgBox("Use this number in the calculation?", MsgBoxStyle.Yes No) = MsgBoxResult.Ye s Then
txtNum1.Text = lstResults.Text
End If
End If
If lstResults.Sele ctedIndex = -1 Then
MsgBox("no number is selected.")
Exit Sub
End If
End Sub

End Class

[ubentook]

'--
Try removing the "Return False" code line.
'--

[jac130]

'--
Try removing the "Return False" code line.
'--

don't functions have to return a value? besides, one of the requirements is that i return a value indicating there was a problem

[jg007]

the code that you have for checking the number works fine for me so I am not sure what you are doing wrong, what is the actual error message?

when using it myself I have just created a textbox and a button and used the same textbox text for both values

Public Class Form1

    Function checknumber(ByVal num1 As String, ByVal num2 As String) As Boolean
        If Not IsNumeric(num1) Then
            MsgBox("Input must be a number.")
        ElseIf Not IsNumeric(num2) Then
            MsgBox("Input must be a number.")
            Return False
        End If
    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        checknumber(TextBox1.Text, TextBox1.Text)

    End Sub

End Class

you might also want to try catching the values as they are enterend using something like this -

 Public Sub checknumber(ByVal sender As System.Object, ByVal key As KeyPressEventArgs) Handles TextBox1.KeyPress

        If Not IsNumeric(key.KeyChar) Then
            MsgBox("Input must be a number.")
            key.Handled = True
        End If

    End Sub

[jac130]

the code that you have for checking the number works fine for me so I am not sure what you are doing wrong, what is the actual error message?

when using it myself I have just created a textbox and a button and used the same textbox text for both values

Public Class Form1

    Function checknumber(ByVal num1 As String, ByVal num2 As String) As Boolean
        If Not IsNumeric(num1) Then
            MsgBox("Input must be a number.")
        ElseIf Not IsNumeric(num2) Then
            MsgBox("Input must be a number.")
            Return False
        End If
    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        checknumber(TextBox1.Text, TextBox1.Text)

    End Sub

End Class

you might also want to try catching the values as they are enterend using something like this -

 Public Sub checknumber(ByVal sender As System.Object, ByVal key As KeyPressEventArgs) Handles TextBox1.KeyPress

        If Not IsNumeric(key.KeyChar) Then
            MsgBox("Input must be a number.")
            key.Handled = True
        End If

    End Sub

i dont get an error message, the program just crashes and highlights the code : num1=txtnum1.te xt, or which ever text box i put the letter into. this is my function:
public Class Form1
Function checknumber(ByV al num1 As String, ByVal num2 As String) As Boolean
If Not IsNumeric(num1) Then
MsgBox("Input must be a number.")
ElseIf Not IsNumeric(num2) Then
MsgBox("Input must be a number.")
Return False
End If
End Function

and this is how i called it in the addition procedure:

Private Sub btnEquals_Click (ByVal sender As System.Object, ByVal e As System.EventArg s) Handles btnEquals.Click
Dim num1, num2 As Double
num1 = txtNum1.Text
num2 = txtNum2.Text

If cmbOperation.Te xt = "Addition" Then
checknumber(num 1, num2)
'calculate result
addition(num1, num2)

[jg007]

this might sound stupid but are you sure you are using the correct textbox name etc and you haven't put a break or something there?

also the other thought as I am writing this is that if you are trying to assign a string to an integer you will get errors and you would need to make sure that num1 or whatever is set as a string, alternatively check if it is numeric before trying to assign it to an integer :)

[jac130]

this might sound stupid but are you sure you are using the correct textbox name etc and you haven't put a break or something there?

also the other thought as I am writing this is that if you are trying to assign a string to an integer you will get errors and you would need to make sure that num1 or whatever is set as a string, alternatively check if it is numeric before trying to assign it to an integer :)

yeah, the txtbox names are all correct. Every other part of the calculator works properly. maybe i'm not calling it correctly, and i have changed the parameters to "as integers" , but still it crashes and hightlights the code of which ever txtbox i put the letter into. and says "conversion from string "e" to type double is not valid"

here's the function now, and how i've called it:


Function checknumber(ByV al num1 As Integer, ByVal num2 As Integer) As Boolean
If Not IsNumeric(num1) Then
MsgBox("Input must be a number.")
ElseIf Not IsNumeric(num2) Then
MsgBox("Input must be a number.")
Return False
End If
End Function

Private Sub btnEquals_Click (ByVal sender As System.Object, ByVal e As System.EventArg s) Handles btnEquals.Click
Dim num1, num2 As Double
num1 = txtNum1.Text
num2 = txtNum2.Text

If cmbOperation.Te xt = "Addition" Then
If Not checknumber(num 1, num2) Then
Exit Sub
End If
'calculate result
addition(num1, num2)

[jg007]

not being funny but there is your problem, you cannot convert a character to a double value!, it you read the message it will explain what is going wrong!

you are trying to convert what is a string value ( example 'A' ) to a double which cannot be done so you need to check if it is numeric BEFORE assigning it!

example code -

if isnumb ( numb1 , numb2 )  then 
num1 = textbox1.text
num2 = texbox2.text
' your code goes here
else 
msgbox ( "Please enter numbers only!")
end if

and the function -

function isnumb ( byval num1 as string , byval numb2 as integer )

dim numericyes as boolean = false

if isnumeric(num1) and isnumeric(num2) then 
numericyes = true
return numericyes
else
return  numericyes
end if

end function

sorry I an being too lazy to load vb to confirm it but this code should be roughly correct :)

[NeoPa]

This thread is not only double-posted, it is also a homework question without [ CODE ] tags. A hat-trick of offenses.

I would ask all responders to remember that our rules prohibit such questions and that direct responses (simply providing answers) are not allowed either. Please see his other thread (VB 08 Calculator) for an example of how help should be provided to such questions when, and only when, the OP conforms to the correct format for asking for help in these circumstances.

Jac130, This is an official site warning. As both offenses occured before you received the first warning it will be treated as a single offense. You should be aware though, that subsequent offenses will result in a temporary ban of your account, followed by a permanent ban if further offenses occur after that.

Administrator.