Input box and null string values

Question

For the following input box, why does the "case" statement not evaluate but the "If" does? I've declared strInputVal as a string.

strInputVal = InputBox("How many payments?")

This works:

 If strInputVal = ""   
 Then GoTo Exit_sub  
 End If

Below does not work:

Select Case IsNumeric(strInputVal)
     Case strInputVal = vbNullString
         GoTo Exit_sub
     End select

your case statement is incorrect. The case statement equats the select case statement. so what your select case isnumeric(strinputval) will return either a true or a false. Those what you case statement should be looking for. case true or case false. change to select case strinputval and case vbnullstring. Se my answer below — Scott Craner, Aug 27 '15 at 20:34

score 0 · Answer 1 · answered Aug 27 '15 at 20:38

0

the case statement should read

Select Case strInputVal
    case vbnullString
        GoTo Exit_sub
end select

answered Aug 27 '15 at 20:38

Scott Craner

score 0 · Answer 2 · edited May 23 '17 at 12:23

You have stumbled upon a unique syntax for Select Case

I think of it as Select Case True. It is an alternate to the If..else if structure.

With this syntax each case is evaluated to a Boolean and compared to the Boolean which you provide.

So doing some of the evaluations, your code is equivalent to this:

Select Case False
   Case "" = vbNullString ' skipped because not False
     GoTo Exit_Sub
End Select

I think what you meant to do is the more standard case syntax:

Select case strInputVal
  case vbEmptyString
    GoTo Exit_Sub
End Select

But you could have written it like this:

Select Case True
   Case "" = vbNullString ' not skipped, because true
     GoTo Exit_Sub
End Select

Thanks for the explanation. – user1863490 Sep 01 '15 at 15:28 — user1863490, Sep 01 '15 at 15:28

2 Answers2