Validation?

[VBdotnet_newbie]

Hello i was wondering if someone could please help me out?

I need to validate some text boxes in my vb.net program so when a user inputs the wrong data a display message is shown telling them what they need to enter.

can anyone tell me what code i would need to perform this, i have 8 text boxes in total, 2 are for text and 6 for numbers!

Thanks alot

Dave

[squirrelly1]

Well, validation is a pretty huge subject because of all of the possibilities and different inputs that you could receive...

Instead of validating the text... I would only let them enter what you want them to by using the Mask Edit (Masked Edit maybe?) control within VB...

Using this control, you can put an "input filter" of sorts in place and only allow them to enter numbers (to a certain length even) or characters...


If you really want to get down to the nit'n'gritty of it... I would do a loop through the char array (string) (yes, they are arrays) and check each of the chars or numbers against a set of chars or numbers that you want to allow...

something like..

For i = 0 to string.length
  If not string.char(i) > "a" and not string.char(i) < "z" ...  etc..  Then
    return false
  end if
next i

Squirrelly1

[VBdotnet_newbie]

Humm thanks sounds qute complicated, think ill just try the input filter.

what code would i need for a simple ext button?

Thanks

[squirrelly1]

an ext button? please explain

[squirrelly1]

It's not really complicated... Just might take a little time to implement correctly... that's all


~Squirrelly1

[VBdotnet_newbie]

Originally posted by squirrelly1
an ext button? please explain

sorry that was meant to be an exit button

[mendhak]

Simple exit?

Me.Close()

[VBdotnet_newbie]

lol ok thanks thats great!

[alextyx]

I use 'masked edit', but there are some little problems. I was not able to intercept keys on that control and there is not a 'readonly' property to use, like is for texboxes.
I prefer to control input by code. Here is an example of how to permit only a numeric input by Keyboard (It doesn't cover input from Ctrl+V !).
In Keypress event of your textbox:

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

That's all. Now it accepts only digits. You can do the same for letters:

If Not Char.IsLetter(e.KeyChar) Then e.Handled = True

and so on.....
If you need to accept, for example: digit, control chars, a decimal separator like "," and a limit of maximum 2 decimal digits:

Private Sub testi(ByRef casella As TextBox, ByVal car As Char, ByRef bool As Boolean)
        If (casella.Text.IndexOf(",") >= 0 And car = ",") Then bool = True
        If (Char.IsDigit(car) Or car = "," Or Char.IsControl(car)) = False Then
            bool = True
        End If
        If (casella.Text.IndexOf(",") > 0 And Char.IsControl(car) = False) Then
            If casella.Text.Substring(casella.Text.IndexOf(",")).Length > 2 Then
                bool = True
            End If
        End If
    End Sub

You can call, always in keypress event, a routine like that above, as in this example:

Private Sub txbEuro1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txbEuro1.KeyPress
                Me.testi(txbEuro1, e.KeyChar, e.Handled)
            End Sub

You have to spend a little of time, but when you'll be more confident with this approach you'll really be able to do everything you need with your textboxes

Good job

[VBdotnet_newbie]

i've tried that but im getting this error back

'KeyChar' is not a member of 'System.EventArgs'.
'Handled' is not a member of 'System.EventArgs'.

the above example would work fine i just want basic validation just so that there is only text in one and numbers in the other?

Thanks

Dave

[squirrelly1]

Why don't you just check against the ascii values of each of the characters in the string??? It's really a simple loop to implement...

Take a look at the System.Text.Ascii...whatever... object... It shouldn't take long to figure out how to use it...

Squirrelly1

[VBdotnet_newbie]

yeh i would but the code alextyx seems to be pritty straight forward!

just can't understand them errors!!!

[stems]

Do a search on the microsoft site for validatingtextboxes and there is an example class to do this. I modified this class to handle also Combo Boxes and found it very good.

[alextyx]

Dear friend, I think you missed the right event. You must put the code in KeyPress event routine, not KeyDown or KeyUP:

This first version permits digit only, the second also control chars (you need them, I think!)

Private Sub txbEuro1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txbEuro1.KeyPress
       
        If Not Char.IsDigit(e.KeyChar) Then e.Handled = True
       
    End Sub
 
 
   Private Sub txbEuro1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txbEuro1.KeyPress
 
               If Not (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar)) Then e.Handled = True
  
    End Sub

Try once again
I'm waiting for your positive answer

[VBdotnet_newbie]

sorry Firend, what is KeyPress how do i create this??

[squirrelly1]

It's an event.

You don't create it.

It's already there for anything that you could think about pushing a key on.

In your coding window, find the control in the left hand combo box and then find "KeyPress" in the right hand list.



Squirrelly1

[VBdotnet_newbie]

yeah sorted that now thanks.

tried both bits of code on each the

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

works fine for entering numbers.

i can't get the other one working just seems the same won't let me enter any text only numbers?

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

????

Thanks

[robymix]

If you want to enter letters use Char.IsLetter(e.KeyChar)

[alextyx]

Robymix was right! The second example I gave to you, it's useful because you can use some control keys! Good job

[VBdotnet_newbie]

do u know if i could use this code

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

and limit the field size so only 2 digits can be entered?

Thanks