NaN

[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???

[MrPolite]

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)

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.

[kryton]

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...

[kryton]

hey it's okay

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

all i did was this...hehe..

[Athley]

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.

<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

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