Validating text entered into a VB text box

[Dorza]

Ok im makeing a program which asks a question and the user has to enter an answer into a txt box. When they do this an OK button appears and when that is clicked it tells them if their question is right or wrong. The problem i have is answers can only be numbers and not letters. How do i get the "ok" button to validate the answer in the text box. If a number is entered the program just gives feed back to the answer . If any thing other than a number is entered it displays a message saying "only numbers can be entered" for example. How do i do this? thanks for anyhelp.

Edit: I know how to do all the other things mentioned. Its just that validation thing i cant work out

[Shad]

If not isNumeric(val) then...

[Mart]

In this situation it is better to prevent the user from entering letters in the text box rather than wait til they press the OK button.

What you need to do is handle the KeyPress event and check which key was pressed. If you set the keycode to 0 they the KeyPress is effectively cancelled.

In the code below all key presses are cancelled apart from 0 to 9...

Private Sub Text1_KeyPress(KeyAscii As Integer)
    Select Case KeyAscii
        Case Asc("0") To Asc("9")
            ' Do nothing
        Case Else
            KeyAscii = 0
    End Select
End Sub

[eldren]

Note that Mart's method will not work if the user pastes text using the right-click pop-up menu. Note also that Mart's method prevents the user from pressing backspace (ASCII char 8, I think).

Private Sub Text1_KeyPress(KeyAscii As Integer)
    Select Case KeyAscii
        Case Asc("0") To Asc("9"), 8 'Allow backspace
            ' Do nothing
        Case Else
            KeyAscii = 0
    End Select
End Sub

Private Sub Text1_Change()
    Dim i as Long, sTemp as String

    For i = 1 To Len(Text1)
        If Instr(1, "0123456789", Mid$(Text1, i, 1)) > 0 Then sTemp = sTemp & Mid$(Text1, i, 1)
    Next

    Text1 = sTemp
End Sub

That ought to do it. Mind you, I don't currently have VB installed, so the counting might be off, in which case, change "For i = 1" to "For i = 0". Hopefully, though, it's right. Stupid 1-based counting.

[Mart]

Note Mart is a VC++ programmer not a VB programmer

[eldren]

Fairly nice code you got there for a non-VB programmer.

Myself, I'm currently employed coding VB. Though I know several other languages, a smidgeon of VC++ too.

[Dorza]

Nice one. thanks everyone

[Dorza]

Re opening an old post

as i said above thanks for all your help. the code eldren provided worked best for my situation however i now need prevent the user from entering zero first then enter numbers after it e.g. 0333. However they are allowed to enter zeros after a first number is entered whcih is not zero e.g. 10350. How is this done? took 0 away from the list of allowed character but realized then that no 0 could be entered which is where i got stuck. lol any ideas?

[eldren]

First, declare a module-level variable that will tell us whether there is a number in the textbox or not. For example: Private blnAllowZero As Boolean

Now, in the Keypress sub, change 'Asc("0") To Asc("9")' to 'Asc("1") To Asc("9")'. Next, in the same Select block, add a case for zero itself, 'Case Asc("0")'. Inside that, put: If blnAllowZero = False Then KeyAscii = 0 'Block 0 if not allowed

Lastly, in the Change sub, add the following at the end, just before End Sub: blnAllowZero = (Len(Text1) > 0)


Hope you come right. :>

[hell_flame85]

You could try this it basicly makes your textbox an interger

Private Sub Button_Click()

    Dim number As Integer
        'here the varible number is dimed as a interger (number)
        
    On Error Resume Next
        'if it errors which it will if anything but a number is entered_
         resume next
        
    number = Text1.Text
        'text is number which is a interger numbers only
        
    If Err <> 0 Then MsgBox ("number only") Else  
        'if it errors then message else do what you want it to do
End Sub