What do you think of this newbie to VB6 error checking routine?

Hi guys,

I wrote this standard module, NumericInputErrorCheck, used to validate thatthe input from a text box is a numeric integer between the values of MinVal & MaxVal:



Option Explicit
Dim Message As Integer, N As Integer

Public Function NumericInputErrorCheck(TextInput As TextBox, MinVal As Integer, MaxVal As Integer) As Boolean

NumericInputErrorCheck = True

For N = 1 To Len(TextInput)
If Asc(Mid(TextInput, N, 1)) < 48 Or Asc(Mid(TextInput, N, 1)) > 57Then NumericInputErrorCheck = False: Exit For
Next N

If TextInput = "" Or Val(TextInput) < MinVal Or Val(TextInput) > MaxVal Or Val(TextInput) <> Int(Val(TextInput)) Or NumericInputErrorCheck = False Then
Message = MsgBox("Please enter an integer between " & MinVal & " and " & MaxVal & ".", vbExclamation, "Error")
NumericInputErrorCheck = False
TextInput.SetFocus
TextInput.Text = ""
End If

End Function



Which seems to work a treat when I call from a textbox subroutine:

Private Sub txtInput_KeyDown(KeyCode As Integer, Shift As Integer)
If KeyCode = vbKeyReturn Then If NumericInputErrorCheck(txtInput, 1, 10) Then Print "Correct!"
End Sub


BUT I have a few queries...
1) Do you think this is the best was of error checking for an integer value?
2) Why does my system beep when I hit return? Any way of stopping it?
3) In the standard module is it necessary to declare Option Explicit?
4) In the standard module should the variables Message & N be declared within the function itself?
5) Why does 'If KeyCode = vbKeyReturn Then If NumericInputErrorCheck....'work but 'If KeyCode = vbKeyReturn and NumericInputErrorCheck....' callsthe function any time a key is pressed? I thought the whole point of AND was that both arguments had to be valid.

Your feedback would be much appreciated guys

"xyzzy" <xyzzy1974@gmail.com> wrote in message
news:653bdff7-41f4-4ade-aa97-413f25c5e32c@googlegroups.com...
>Hi guys,

<snip>

>BUT I have a few queries...
>1) Do you think this is the best was of error checking for an integer
>value?
>2) Why does my system beep when I hit return? Any way of stopping it?
>3) In the standard module is it necessary to declare Option Explicit?
>4) In the standard module should the variables Message & N be declared
>within the function itself?
>5) Why does 'If KeyCode = vbKeyReturn Then If NumericInputErrorCheck....'
>work but 'If KeyCode = vbKeyReturn and >NumericInputErrorCheck....' calls
>the function any time a key is pressed? I thought the whole point of AND
>was that both arguments >had to be valid.

>Your feedback would be much appreciated guys

You might want to look at the IsNumeric function, it'll save you a bit of
effort.



You can suppress the beep by adding:

If KeyAscii = vbKeyReturn Then KeyAscii = 0

to the KeyPress event



ALWAYS use Option Explicit, without it typing errors can go undetected



Scope: If a variable is only used in one routine then it should be declared
in that routine, if a variable spans multiple routines then as a module
variable.



AND does work that way, all parameters have to be evaluated - even if the
first one fails any subsequent ones will still be worked out.



DaveO

On Thursday, August 9, 2012 10:10:01 AM UTC+1, DaveO wrote:

<snip>

> You might want to look at the IsNumeric function, it'll save you a bit of
> effort.

Right. See below.

> You can suppress the beep by adding:
> If KeyAscii = vbKeyReturn Then KeyAscii = 0
> to the KeyPress event

That's brilliant!

If KeyAscii = vbKeyReturn Then KeyAscii = 0: If
NumericInputErrorCheck(txtInput, 1, 10) Then Print "Correct!"

Works a treat.

> ALWAYS use Option Explicit, without it typing errors can go undetected

Sure.

> Scope: If a variable is only used in one routine then it should be declared
> in that routine, if a variable spans multiple routines then as a module
> variable.

OK. There is only the one function in the standard module.

> AND does work that way, all parameters have to be evaluated - even if the
> first one fails any subsequent ones will still be worked out.

Gotcha. So Vesion 2:

Option Explicit

Public Function NumericInputErrorCheck(TextInput As TextBox, MinVal As
Integer, MaxVal As Integer) As Boolean

Dim Message As Integer

If (Not IsNumeric(TextInput)) Or (Val(TextInput) < MinVal) Or (Val
(TextInput) > MaxVal) Or (Val(TextInput) <> Int(Val(TextInput))) Then
Message = MsgBox("Please enter an integer between " & MinVal & " and " &
MaxVal & ".", vbExclamation, "Error!")
TextInput.SetFocus
TextInput.Text = ""
Exit Function
End If

NumericInputErrorCheck = True

End Function

BTW note that I have enclosed each comparison operation within brackets so it's easier to undersand at a glance. Is this considered bad programming practice?

Also, can we not declare Message as type Byte (seems to work ok) or by convention you declare it as an integer?

Thanks for your help!

On 09/08/2012 11:12, xyzzy wrote:
> Also, can we not declare Message as type Byte (seems to work ok) or
> by convention you declare it as an integer?

It should actually be VbMsgBoxResult which is an enum (internally an
integer type)

> Message = MsgBox("Please enter an integer between " & MinVal & " and
> " & MaxVal & ".", vbExclamation, "Error!")

But as you're not asking a question, why both with the answer?

> MsgBox "Please enter an integer between " & MinVal & " and " & MaxVal
> & ".", vbExclamation, "Error!"
Would work just as well.

--
Deanna Earley (dee.earley@icode.co.uk)
i-Catcher Development Team
http://www.icode.co.uk/icatcher/

iCode Systems

(Replies direct to my email address will be ignored. Please reply to the
group.)

On Thursday, August 9, 2012 11:45:24 AM UTC+1, Deanna Earley wrote:

> It should actually be VbMsgBoxResult which is an enum (internally an
> integer type)

Interesting. Enumerations look useful.

> But as you're not asking a question, why both with the answer?
>
> > MsgBox "Please enter an integer between " & MinVal & " and " & MaxVal
> > & ".", vbExclamation, "Error!"
>
> Would work just as well.

Well yes I always wondered this. I quote from my Learn VB6 manual: 'Although Visual Basic still supports the MsgBox statement, Microsoft recommends that you use only the MsgBox() function because of its inspection ability fora return value.' That was why - I wanted to do it 'properly', but, as Microsoft no longer supports VB6, what the hell

On Thursday, August 9, 2012 11:45:24 AM UTC+1, Deanna Earley wrote:

> It should actually be VbMsgBoxResult which is an enum (internally an
> integer type)

Interesting. Enumerations look useful.

> > Message = MsgBox("Please enter an integer between " & MinVal & " and
> > " & MaxVal & ".", vbExclamation, "Error!")
>
> But as you're not asking a question, why both with the answer?
>
> > MsgBox "Please enter an integer between " & MinVal & " and " & MaxVal
> > & ".", vbExclamation, "Error!"
>
> Would work just as well.

Well I always wondered this. My Learn VB manual says that although VB6 still suppoerts the MgsBox statement, Microsoft recommends using the MsgBox function for its ability to return values - but as Microsoft no longer suppoerts VB6 what the hell!

On Thursday, August 9, 2012 12:28:04 PM UTC+1, xyzzy wrote:
..
..
> Well I always wondered this...

This throws up another question. My standard module code is now:


Option Explicit

Public Function NumericInputErrorCheck(TextInput As TextBox, MinVal As Integer, MaxVal As Integer) As Boolean

If (Not IsNumeric(TextInput)) Or (Val(TextInput) < MinVal) Or (Val(TextInput) > MaxVal) Or _
(Val(TextInput) <> Int(Val(TextInput))) Then
MsgBox "Please enter an integer between " & MinVal & " and " & MaxVal & ".", vbExclamation, "Error!"
TextInput.SetFocus
TextInput.Text = ""
Exit Function
End If

NumericInputErrorCheck = True

End Function


Question: I guess there is no need now for the Option Explicit?

On 09/08/2012 12:28, xyzzy wrote:
> On Thursday, August 9, 2012 11:45:24 AM UTC+1, Deanna Earley wrote:
>>> Message = MsgBox("Please enter an integer between " & MinVal & " and
>>> " & MaxVal & ".", vbExclamation, "Error!")
>>
>> But as you're not asking a question, why both with the answer?
>>
>>> MsgBox "Please enter an integer between " & MinVal & " and " & MaxVal
>>> & ".", vbExclamation, "Error!"
>>
>> Would work just as well.
>
> Well I always wondered this. My Learn VB manual says that although
> VB6 still suppoerts the MgsBox statement, Microsoft recommends using
> the MsgBox function for its ability to return values - but as
> Microsoft no longer suppoerts VB6 what the hell!

It's still a function, you're just ignoring the return value.
The Manual doesn't list it as a statement:
http://msdn.microsoft.com/en-us/libr...(v=vs.60).aspx

Also, why are you learning a 15 year old language and obsoleted 5 (very
soon to be 6?) times IDE?

While there is still a large pool of VB6 code out there, I wouldn't want
to get into the maintenance market at this stage.
There are many more capable and newer languages and environments to
choose from.

--
Deanna Earley (dee.earley@icode.co.uk)
i-Catcher Development Team
http://www.icode.co.uk/icatcher/

iCode Systems

(Replies direct to my email address will be ignored. Please reply to the
group.)

On Thursday, August 9, 2012 12:44:05 PM UTC+1, Deanna Earley wrote:

> It's still a function, you're just ignoring the return value.
> The Manual doesn't list it as a statement:
> http://msdn.microsoft.com/en-us/libr...(v=vs.60).aspx

OK. I presumed functions always had brackets after the keyword.

> Also, why are you learning a 15 year old language and obsoleted 5 (very
> soon to be 6?) times IDE?
> While there is still a large pool of VB6 code out there, I wouldn't want
> to get into the maintenance market at this stage.

Excellent question. I guess it's because I'm used to VB6 & don't like VB.Net & can't be asked to learn another dialect of Basic. VB6 lets me throw applications together quickly & I do it just for fun.

> There are many more capable and newer languages and environments to
> choose from.

Out of interest, if I could be asked, what would you recommend?

On 09/08/2012 12:56, xyzzy wrote:
> On Thursday, August 9, 2012 12:44:05 PM UTC+1, Deanna Earley wrote:
>> There are many more capable and newer languages and environments to
>> choose from.
>
> Out of interest, if I could be asked, what would you recommend?

It's difficult to say, as I'm not a newbie (no offence , I use
whatever is suitable for what I'm doing
I have 12 years professional VB6 experience and I can't remember how
many before that. Most of my time is spent on the 10 years of legacy VB6
code with most (not all) new code being in C# 2.0.
My colleague primarily uses C++ as most of it communicates with
hardware, Direct3D, etc.

If I was starting from scratch, I'd probably try C# 4.0/WPF "as it's
new" and I can get an IDE for free (#develop and VC# express)

YMMV though. If you have the experience with VB6 (I assumed you didn't
from the "newbie to VB6") then you can stick with it.

--
Deanna Earley (dee.earley@icode.co.uk)
i-Catcher Development Team
http://www.icode.co.uk/icatcher/

iCode Systems

(Replies direct to my email address will be ignored. Please reply to the
group.)

On Thursday, August 9, 2012 1:43:47 PM UTC+1, Deanna Earley wrote:

> YMMV though. If you have the experience with VB6 (I assumed you didn't
> from the "newbie to VB6") then you can stick with it.

Well I have some limited experience, but now, as I have some free time on my hands, I thought I'd get down & learn it properly. I'll probably look around at other dialects of Basic after that. C++ & C# I am not a fan of. Thanks for your feedback

| > YMMV though. If you have the experience with VB6 (I assumed you didn't
| > from the "newbie to VB6") then you can stick with it.
|
| Well I have some limited experience, but now, as I have some free time on
my hands, I thought I'd get down & learn it properly. I'll probably look
around at other dialects of Basic after that. C++ & C# I am not a fan of.
Thanks for your feedback


These days, any discussion of programming languages
has to take Microsoft's plans into account. Except for
being limited to 32-bit, VB is arguably the best supported
tool on all Windows versions. (Even C++, if used in VS,
will almost always require a sizable runtime installation
on many machines -- unless one uses an older version.)

On the other hand, if Microsoft is successful with the
Metro-everywhere strategy, writing software on Windows
may not have much of a future. One can use .Net, C++,
or even script on Metro, but the only option is to write
phone/tablet trinkets, approved by Microsoft and sold
through their store. (With them getting a 30% cut.)

It's not hard to imagine a scenario in the near future
where actual computer software programs may only be
available on Linux or by pseudo-Web subscription. (I say
pseudo-Web because the cloud craze is mainly a money-
making scheme. The actual logistics are secondary. One
could have a massive program installed locally, but if a
webpage login is required to use that program then it
will be known as a cloud subscription.)

Adobe is already selling Photoshop in a 3-month subscription
version. MS is trying to make MS Office into a Web
business. Etc.)

Something Like The Code Below May Be A Bit Wiser if you really need to check
the value before user can do anything else :0)

Ivar

Option Explicit

Public Function NumericInputErrorCheck(StrVar, MinVal As Integer, MaxVal As
Integer) As Boolean
Dim TestInt As Integer
TestInt = CInt(Val(StrVar))
Select Case True
Case TestInt <> StrVar, TestInt < MinVal, TestInt > MaxVal, Not
IsNumeric(StrVar)
Case Else
NumericInputErrorCheck = True
End Select
End Function

Private Sub txtInput_KeyPress(KeyAscii As Integer)
Dim BoolVar As Boolean
If KeyAscii = vbKeyReturn Then
KeyAscii = 0
txtInput_Validate BoolVar
If Not BoolVar Then
'NextControl.SetFocus
End If
End If
End Sub

Private Sub txtInput_Validate(Cancel As Boolean)
If Not NumericInputErrorCheck(txtInput.Text, 1, 10) Then
Cancel = True
MsgBox "Please Enter A whole Number Between 1 and 10.", vbExclamation,
"Invalid Input"
txtInput.SelStart = 0
txtInput.SelLength = Len(txtInput.Text)
End If
End Sub

"xyzzy" <xyzzy1974@gmail.com> wrote in message
news:44317642-083d-48c3-8e57-962384261432@googlegroups.com...
> On Thursday, August 9, 2012 12:28:04 PM UTC+1, xyzzy wrote:

> If (Not IsNumeric(TextInput)) Or (Val(TextInput) < MinVal) Or
> (Val(TextInput) > MaxVal) Or _

Except in certain cases such as Label = "Hello World" I would avoid relying
on default properrties so the above should really be:
If (Not IsNumeric(TextInput.Text)) Or (Val(TextInput.Text) < MinVal) Or
(Val(TextInput.Text) > MaxVal) Or _

You asked earlier about brackets, if they make to expression clearer and
avoid ambiguous evaluation then yes, the more the merrier. There is no
problem with the brackets in the above line.



>Question: I guess there is no need now for the Option Explicit?

Wrong, wrong and a thousand times wrong!

It may well be OK now but if you return and add something else later and
were to type "MinVa1" instead of "MinVal" (Number 1 instead of lower case L)
without Option Explicit you could search for the weird error for weeks, with
Option Explicit it just won't run and will highlight the typo.

I'd strongly suggest going to the Tools/Options menu and ticking "Require
Variable Declaration". This will automatically add "Option Explicit" to all
new forms and modules when they are first created.




DaveO

"Ivar" <ivar.ekstromer000@ntlworld.com> wrote in message
news:FWPUr.1066144$3s1.921011@fx12.am4...

> Select Case True

This is not going to end well!

I think I'll sit back and wait for the inevitable opprobrium

:-)

DaveO.