NaN

hi
how to i make an expection when the user input a char??

example
dim n,m,p as Double
n=textbox.text
m=textbox2.text
p= m-n

etc...i know it's NaN but how to declare or write them???

Quote:

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Originally posted by kryton
hi
how to i make an expection when the user input a char??

example
dim n,m,p as Double
n=textbox.text
m=textbox2.text
p= m-n

etc...i know it's NaN but how to declare or write them???

---

what you are doing would give you an errror anyways (if you have option strict on, which you should)

VB Code:

Option Strict On ' Put this at the top top top top top part of the code, not in a subrutine
 
' in a sub:
dim n,m,p, as double
try
    n = cdbl(textbox.text)
    m = cdbl(textbox2.text)
    p = m-n
catch
' probably an invalid character was entered... handle the exception here
end try

I dont know what you want to do with Nan? I think a NaN is "not a number"? I cant remember. It's basically something undefined. I think if you set your variable to something/0, it's gunno be nan.

i wanted the program to be able to catch is the user input a char instead of a number..

like if the program asked the user to input age and he/she input "abc", it will appear a msgbox to tell the user to input a number...

hey it's okay

ElseIf Not IsNumeric(Booked.Text) Then
MsgBox("Entry must be numeric")

all i did was this...hehe..

One solution might be not to catch anything but to prevent the user from being able to type text. I made my own "NumberBox" for this, maybe it might be useful for someone. :)

Code:

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<System.Drawing.ToolboxBitmap(GetType(System.Windows.Forms.TextBox))> _
Public Class NumberBox
    Inherits System.Windows.Forms.TextBox
    Protected Overrides Sub OnKeyPress(ByVal e As System.Windows.Forms.KeyPressEventArgs)
        If Not Char.IsNumber(e.KeyChar) AndAlso Not (Strings.Asc(e.KeyChar) = 8) Then
            e.Handled = True
        End If
    End Sub
End Class

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When a character is pressed nothing happens, but if a number och backspace is pressed it works as anormal textbox.