[RESOLVED]UBound giving subscript out of range

[mysticmusician]

I have an array
Dim A() As String

this is initially not initialized so I do this in a function (this function is called multiple tiles)
Max = Ubound(A)

If Max = 0 Then
Redim A(Max+1,Max+10) As String
End IF

This UBound gives me a error saying Subscript out of range. How can I check if a array is initialized previously or not. It works if the array had some value but fails first time.

[vbasicgirl]

work around this

If (Not A) = -1 Then
 'not been initialized
End If

casey.

[szlamany]

work around this

If (Not A) = -1 Then
 'not been initialized
End If

casey.

That won't work at all - NOT A has nothing to do with the ARRAY of A.

Simply change your logic a small bit:

Dim A() as String
Redim A(0,0)

...then later on...

Max = UBound(A) ' Note that UBound needs to specify which dimensional of the arry - if two dimensional

[vbasicgirl]

i answered the question

How can I check if a array is initialized previously or not.

casey.

[RhinoBull]

work around this

If (Not A) = -1 Then
 'not been initialized
End If

casey.

Sorry, casey, but it's a total absurd ...

[szlamany]

Private Sub Form_Load()

Dim a() As String

If Not a Then Debug.Print "A is not initialized"

ReDim a(1, 1)

If Not a Then Debug.Print "A is still not initialized - since NOT A does not check for that!"

End Sub

[edit] - please note that VBasicGirl's example does in fact work.

[vbasicgirl]

are you saying this doesnt work for you ?

Dim A() As String
 
If (Not A) = -1 Then
 Debug.Print "array as not been initialized"
Else
 Debug.Print "array as been initialized"
End If
 
ReDim A(1)
 
If (Not A) = -1 Then
 Debug.Print "array as not been initialized"
Else
 Debug.Print "array as been initialized"
End If

casey.

[vbasicgirl]

i found the original explanation.


If a dynamic array has not been redimmed, or has been erased, then it does not yet point to a SAFEARRAY structure. Unfortunately, you cannot test if the arrayname = 0. But, you can binary NOT it and make a comparison on the result.

(Not 0) = -1 ' not redimmed or erased
(Not SomePointer) <> -1 ' redimmed

Why MS didn't include a simple function IsRedimmed, I'll never understand.


casey.

[vbasicgirl]

i dont know if this is allowed, a link to the forum thread i found it.

delete if not allowed.

http://www.xtremevbtalk.com/showthre...ght=impressive

casey.

[szlamany]

i found the original explanation.


If a dynamic array has not been redimmed, or has been erased, then it does not yet point to a SAFEARRAY structure. Unfortunately, you cannot test if the arrayname = 0. But, you can binary NOT it and make a comparison on the result.

(Not 0) = -1 ' not redimmed or erased
(Not SomePointer) <> -1 ' redimmed

Why MS didn't include a simple function IsRedimmed, I'll never understand.


casey.

Wow - I must admit that I was very, very wrong - your example does in fact work. What an odd technique to arrive at an array having been already dimensioned!

I still stand by my method though - simply REDIM that array immediately and no need to check for whether it's been initialized yet. But that's just my personal preference.

Also, I was wrong to state that A() and A where two different variables. That's my confusion from other BASIC/machine platforms I've coded on - that do allow for an A() array and an A variable - unrelated to each other.

Casey - my apologies

[RhinoBull]

Best way for me is as follows:

Option Explicit
 
Dim arText() As String
Dim arNumbers As Integer
 
Private Sub Form_Load()
    Redim arText(0)
    arText(0) = "DUMMY"
    Redim arNumbers(0)
    srNumbers(0) = - 999
End Sub

So, all you really need to do is check if first element is a dummy entry and if YES = change it, if NOT Redim your array. Never failed this logic ...

[szlamany]

RhinoBull - Casey was right - I argued from a position that wasn't very valid!

[vbasicgirl]

for the record, i do agree with you on redimming it firstly, i was just explaining on how you can check.

szlamany - thank you.

[szlamany]

for the record, i do agree with you on redimming it firstly, i was just explaining on how you can check.

szlamany - thank you.

Casey - you are very welcome.

BTW - Whenever we use REDIM (which is infrequently), we like to do it in big jumps - like double the array size each time. When you use REDIM PRESERVE you are moving potentially large amounts of memory around in the process - and based on our old-school thoughts on memory manipulation, we avoid that.

We always have a "long" variable that keeps track of the current position the array is built up to so far - I think that others might use a concept of checking UBOUND and up'ing the limit by 1 to fit another entry in. That's something we avoid.

[mysticmusician]

What I ended up doing is this

Private Declare Function SafeArrayGetDim Lib "oleaut32.dll" (ByRef saArray() As Any) As Long

Then
If (SafeArrayGetDim(EmailArray) > 0) Then
Array initialized
Else
Not Initialized !
End IF

This works perfect.

[RhinoBull]

RhinoBull - Casey was right - I argued from a position that wasn't very valid!

I will dissagree again - in the way it was presented it was a complete nonsense.