Variable declaration question

[Nick via AccessMonster.com]

Hello,

I was wondering if someone could help or point me in the right direction; I
searched but am not even sure of what search terms apply.

I had several string variables declared like this:

Dim strAlreadyAdded, strErrorMessage, strCannotAdd as String

I then tried to pass them to a Sub defined as:

Public Sub Validate_MDI(ByRef strCannotAdd As String, ByRef
strErrorMessage As String, ByRef strAlreadyAdded As String, ByRef Data_Error
As Boolean)

I compiled and received a message saying strErrorMessage (and later,
strAlreadyAdded) had a ByRef argument mismatch. I reorganized by declare
statement to only have one variable per line, and I had no problems.

My question is: When variables are declared in a line like in the first
statement, does VBA carry through the "as String" to all of them? I thought
it did at first, but not I'm not so sure... I use this type of declaration
structure when declaring recordsets, and have never had a problem. I want to
be sure I force declaration, I don't want to leave it up to Access to
"assume" what variable type I want, if that is what it's doing currently.

-Nick

 

[Allen Browne]

Nick, this is an important question, and the answer is No.

The line:
Dim strAlreadyAdded, strErrorMessage, strCannotAdd as String
creates 2 variants (since no type was specified for the first 2), and one
string.

To get 3 strings, use:
Dim strAlreadyAdded As String, strErrorMessage As String, strCannotAdd
as String

Because this syntax does not match what some other programming languages do,
I suggest you use one line for each declaration.

 

[Douglas J Steele]

Actually, while you've declared 3 variables, you've only declared one of
them (strCannotAdd) to be a string: the other two have been declared as
variants.

You can't "short circuit" declarations like that in VBA. To make all 3
strings, you need:

Dim strAlreadyAdded as String, strErrorMessage as String, strCannotAdd as
String

or, of course,

Dim strAlreadyAdded as String
Dim strErrorMessage as String
Dim strCannotAdd as String

 

[Nick via AccessMonster.com]

Very interesting... thanks for both replies. It had never occured to me that
they would not "short circuit" into a string variable until I started looking
at the ByRef data coercion message, and wondered why VBA would coerce a
string into a string. This impacts quite a bit of my program; it is time to
search through and modify my subs.

And sorry for the numerous typos in my first post; it was a Monday morning
and I hadn't had my caffeine.

Again, thanks for the important advice.

-Nick