Calculate the factorial

[Tin]

Dear Sir/Madam,

I have one assignment , which need me to

write a program to calculate the factorial of an integer,

then press the button that would display the result in a label.3

& the program should warn the user if the

iinput is not a number.

I have tried my best to write ,but It show me

something wrong,

What I write is as following, Please help me to show what is going wrong !
Thanks !

Tin



Dim N As Integer = CInt(TextBox1.T ext)
Dim sum As Integer
Dim Factorial As Integer

Try

N = Integer.Parse(T extBox1.Text)

sum = N * Factorial(N - 1)

Label3.Text = CStr(sum)

Catch ex As FormatException
MessageBox.Show ("Number is not an integer. Please enter an Integer ")


End Try

End Sub



Function Factorial(ByVal N As Integer) As Integer
If N = 0 Then
Return 1
Else
Return N * Factoria((N - 1) - 1)
End If
End Function

[willakawill]

Dear Sir/Madam,

I have one assignment , which need me to

write a program to calculate the factorial of an integer,

then press the button that would display the result in a label.3

& the program should warn the user if the

iinput is not a number.

I have tried my best to write ,but It show me

something wrong,

What I write is as following, Please help me to show what is going wrong !
Thanks !

Tin



Dim N As Integer = CInt(TextBox1.T ext)
Dim sum As Integer
Dim Factorial As Integer

Try

N = Integer.Parse(T extBox1.Text)

sum = N * Factorial(N - 1)

Label3.Text = CStr(sum)

Catch ex As FormatException
MessageBox.Show ("Number is not an integer. Please enter an Integer ")


End Try

End Sub



Function Factorial(ByVal N As Integer) As Integer
If N = 0 Then
Return 1
Else
Return N * Factoria((N - 1) - 1)
End If
End Function

Hi, a couple of things might help.
The Try...Catch block is C++ programming and is not part of VB6
You need to make sure that the input number is 171 or less or you will get an overflow error as the factorial of 172 is too large to store in a Double.
You have declared an integer with the same name as the function.

The following works

Private Sub cmdFactorial_Click()
 Dim dblN As Double
 Dim dblFactorial As Double
 
If IsNumeric(TextBox1.Text) _
And Len(TextBox1.Text) < 4 Then
   dblN = CLng(TextBox1.Text)
   If dblN > 170 Then
      MsgBox "Please enter a numeric value between 1 and 170"
      TextBox1.Text = ""
      TextBox1.SetFocus
      Exit Sub
   End If
Else
   MsgBox "Please enter a numeric value between 1 and 170"
   TextBox1.Text = ""
   TextBox1.SetFocus
   Exit Sub
End If
dblFactorial = Factorial(dblN)
TextBox1.Text = dblFactorial
End Sub
 
Private Function Factorial(dblNum As Double) As Double
   If dblNum - 1 = 0 Then
      Factorial = dblNum
      Exit Function
   End If
   Factorial = dblNum * Factorial(dblNum - 1)
End Function