How to stop users typing in anything but numbers in txtbox.

This is a simple one.

How do I make sure I don't get a type miss match error. For example if I have 2 text boxes which I only want integers typed in and not letters how would I code this.

Once I have got the code going, would it be better to make say letters off limits or should I chuck up a msgbox and tell the user that only numbers can be typed?

Is there a way of stopping all but numbers being typed into a textbox?

Thanks

There is a way to only allow numbers without alerting the user that he/she types a wrong character.
Try this code:

VB Code:

Private Sub Text1_KeyPress(KeyAscii As Integer)
    'ensure we only accept numeric input
    KeyAscii = NumericOnly(KeyAscii)
    
End Sub
 
Public Function NumericOnly(KeyAscii As Integer) As Integer
    'if the key passed to this function is not a number
    If Not IsNumeric(Chr$(KeyAscii)) And Not KeyAscii = vbKeyBack Then
        'return 0
        NumericOnly = 0
    Else
        'return the same key
        NumericOnly = KeyAscii
    End If
End Function

Here is a code I am using which only allows type numeric numbers positive or negative and also use . or , for decimal separation depending on Windows configuration

VB Code:

Private Sub Text1_KeyPress(KeyAscii As Integer)
Dim texte As String, decimalpoint As String
decimalpoint = Mid$(Format(0, "0.0"), 2, 1)
texte = Text1.Text
If Text1.SelStart = 0 And Text1.SelLength = 0 And InStr(texte, "-") Then
    KeyAscii = 0
    Exit Sub
End If
If KeyAscii > 31 And (KeyAscii < 44 Or KeyAscii > 57 Or KeyAscii = 47) Then KeyAscii = 0
If (KeyAscii = 46 Or KeyAscii = 44) And (InStr(texte, ".") Or InStr(texte, ",")) Then
    KeyAscii = 0
ElseIf (KeyAscii = 46 Or KeyAscii = 44) Then KeyAscii = Asc(decimalpoint)
End If
If KeyAscii = 45 Then
    If Left$(texte, 1) <> "-" And Len(texte) > 0 Then
        KeyAscii = 0
        Text1.Text = "-" & texte
        Text1.SelStart = Len(Text1.Text)
    ElseIf Len(texte) > 0 Then
        KeyAscii = 0
    End If
End If
End Sub