Alphanumeric validation for textbox | No numbers or characters allowed.

Question

 

Hello everyone,

How can I program a text box so that no number or characters are accepted, only back pace and the tab key.

Thanks everyone!

 

Syn

Answer 1

Hi,

When you press and release a key while a control on a form has the focus (or use the SendKeys action or statement to send a keystroke), the following sequence of events occurs:

KeyDown → KeyPress → KeyUp

If pressing a key triggers another event for a control, the other event occurs after the KeyPress event but before the KeyUp event. For example, if a keystroke changes text in a text box, triggering a Change event, the following sequence of events occurs:

KeyDown → KeyPress → Change → KeyUp

Use these events to determine if an allowed key is pressed. All you need to do is check if a backspace or tab key is pressed, don't check for all keys that are not allowed only keys that are allowed.

Code like this as an example

Private Sub Textbox_KeyDown(KeyCode As Integer, Shift As Integer)
    If (KeyCode <> vbKeyTab Or KeyCode <> vbKeyBack) Then
        KeyCode = 0  'ignore the key
    End If
End Sub

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"The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination." - Fred Brooks

Answer 2

Hi,

When you press and release a key while a control on a form has the focus (or use the SendKeys action or statement to send a keystroke), the following sequence of events occurs:

KeyDown → KeyPress → KeyUp

If pressing a key triggers another event for a control, the other event occurs after the KeyPress event but before the KeyUp event. For example, if a keystroke changes text in a text box, triggering a Change event, the following sequence of events occurs:

KeyDown → KeyPress → Change → KeyUp

Use these events to determine if an allowed key is pressed. All you need to do is check if a backspace or tab key is pressed, don't check for all keys that are not allowed only keys that are allowed.

Code like this as an example

Private Sub Textbox_KeyDown(KeyCode As Integer, Shift As Integer)
    If (KeyCode <> vbKeyTab Or KeyCode <> vbKeyBack) Then
        KeyCode = 0  'ignore the key
    End If
End Sub

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"The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination." - Fred Brooks

Sorry, I noticed all the questions did not get included in the post. This is what I am trying to do. I need the text box to accept only letters, no numbers numbers or symbol. However, I was also meaning that the user should be able to tab in the text box or use the backspace key, but not numbers or symbols.

Thanks again

Answer 3

Hi Synthologic,

 

You might try this, place this Function into a seperate Module and save it, for example: basCharsOnly.

 

Public Function ChkOnlyChars(KeyAscii As Integer)

Dim ctrl As Control
Set ctrl = Screen.ActiveControl

Select Case KeyAscii
    Case Asc("a") To Asc("z")
    Case Asc("A") To Asc("Z")
    Case Asc("-")
        If InStr(1, ctrl.value, "-") > 0 Or ctrl.SelStart > 0 Then
            KeyAscii = 0
        End If
    Case Asc(".")
        If InStr(1, ctrl.value, ".") > 0 Then
            KeyAscii = 0
        End If
    Case Else
        KeyAscii = 0
End Select
  
End Function

_________________________

Then in the KeyPress event of your Textbox, place the following line:

 

Private Sub txtYourTextFieldNameHere_KeyPress(KeyAscii As Integer)

ChkOnlyChars KeyAscii

End Sub

Hope this helps,

 

 

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Daniel van den Berg | Washington, USA | "Anticipate the difficult by managing the easy"