ignore an invalid character in a text box [RESOLVED]

[JMM427]

I am trying to prevent users from entering a character into a text box. I remember doing something like this in a beginning VB .net class a while ago and it was only one line of code in the textchanged (?) event of the textbox. From what I remember, it was a simple command to ignore the key that was pressed if it did not fit a certain criteria. Does anyone know a simple way to do this.

[Lunatic3]

It is in KeyPress event, and is e.Handled=True

[JMM427]

Thank you!

[JMM427]

I tried the following code and it's not working. Am I missing something, or misunderstanding what the handled event does?

Private Sub txtMileage_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtMileage.KeyPress
 
        If e.KeyChar.IsDigit("[0-9]") Then
            e.Handled = True
        Else
            e.Handled = False
 
        End If
 
    End Sub

What I'm trying to do is ignore the key being pressed if it is not a digit?

[JMM427]

Sorry, I tried this also:

Private Sub txtMileage_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtMileage.KeyPress
 
        If e.KeyChar.IsDigit("[0-9]") = True Then
            e.Handled = True
        Else
            e.Handled = False
 
        End If
 
    End Sub

Still does the same thing.

[Lunatic3]

If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar)) Then
     e.Handled = True
End If

[JMM427]

Finally! Thank you.

Now what if I also want it to accept a decimal separator "."?

[Lunatic3]

Because the decimal point will happen only once then you have to do this:

If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar)) Then
     If Not (e.KeyChar = ".") Or (InStr(DirectCast(sender, TextBox).Text, ".", CompareMethod.Text)) Then
          e.Handled = True
     End If
End If

[JMM427]

Thanks, that makes sense. I appreciate all your help.

[sw_is_great]

why donnt u use the method IsDigit