limit textbox keypress to numeric values.

[davidrobin]

In VB6 I would limit the characters allowed in a text box by saying

if keyascii=??? then
    keyascii=0
endif

The ??? being what ever I wanted to compare against
Now with .Net there is only a readonly keychar property.

How do I limit keypresses to numeric values.

[crptcblade]

Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
 
        If e.KeyChar < "0"c Or e.KeyChar > "9"c Then
            e.Handled = True
        End If
 
    End Sub

[yaksplat]

You need to use the keydown and keypress methods for each box that you are limiting. You also have to allow the - and . keys as well as all of the numpad ones.

Keydown calls this

        Private Sub OnlyNumbers(ByVal e As System.Windows.Forms.KeyEventArgs)
        ' Initialize the flag to false.
        nonNumberEntered = False

        ' Determine whether the keystroke is a number from the top of the keyboard.
        If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then
            ' Determine whether the keystroke is a number from the keypad.
            If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then
                ' Determine whether the keystroke is a backspace.
                If e.KeyCode <> Keys.Back Then
                    ' Determine whether the keystroke is a . or a - on either the main keyboard or keypad
                    If e.KeyCode <> Keys.Subtract Then  'keypad
                        If e.KeyCode <> Keys.Decimal Then 'keypad
                            If e.KeyCode <> Keys.OemPeriod Then 'keyboard
                                If e.KeyCode <> Keys.OemMinus Then 'keyboard
                                    ' A non-numerical keystroke was pressed. 
                                    ' Set the flag to true and evaluate in KeyPress event.
                                    nonNumberEntered = True
                                End If
                            End If
                        End If
                    End If
                End If
            End If
        End If
    End Sub

This goes within keyPress:

        ' Check for the flag being set in the KeyDown event.
        If nonNumberEntered = True Then
            ' Stop the character from being entered into the control since it is non-numerical.
            e.Handled = True
        End If

Hope that helps

Jim

[davidrobin]

Now thats more complicated than it used to be.

Thanks.

[davidrobin]

yaksplat
Your code doesn't work at all, I can type anything and everything in the textbox.

crptcblade
Yours is too good, I forgot to mention that I need to allow the backspace button to be pressed.