Re: [libreoffice-users] ReDim of a variable of a custom type

2011/8/18 planas <jslozier@gmail.com>:
> Johnny,
>
> On Thu, 2011-08-18 at 18:11 +0200, Johnny Rosenberg wrote:
>
> > I was, in a reply to another question, told that my questions were way
> > too basic for the dev@api.OpenOffice.org list, so I'll give it a try
> > here instead.
> >
> > I wrote some example code:
> >
> > REM  *****  BASIC  *****
> >
> > Option Compatible
> > Option Explicit
> >
> > Type MyType
> >        a As Integer
> >        b As Integer
> > End Type
> > Dim x(1) As MyType
> >
> > Sub Main
> >        Dim y As MyType
> >        Dim i As Integer
> >        For i=0 To 1
> >                x(i).a=1+i*2
> >                x(i).b=2+i*2
> >        Next i
> >        y.a=5
> >        y.b=6
> >
> >        MsgBox x(0).a & x(0).b & x(1).a & x(1).b & y.a & y.b ' Displays 123456
> >
> >        ReDim x(1) As MyType
> >        ReDim y As MyType
> >        MsgBox x(0).a & x(0).b & x(1).a & x(1).b & y.a & y.b ' Displays 123400
> > End Sub
> >
> > So if we have an array as MyType (or any other custom type, I
> > suppose), ReDim will not reset it.
> > Is this the expected behaviour or should I write a bug report?
> > If it is expected, why?
> >
> > I guess it's unnecessary to mention that I am a complete beginner in
> > everything that has anything to do with computers; we guitar players
> > are quite stupid, you know.
> >
> > Oh, and in case it matters:
> > LibreOffice 3.3.3, Ubuntu 10.10.
> > LibreOffice installed with the debs at http://www.libreoffice.org/.
> >
> > Best regards
> >
> > Johnny ”The Moron” Rosenberg
> > ジョニー・ローゼンバーグ
>
> I had to look up ReDim behavior myself, so do not to hard on yourself.
> ReDim is used to re-dimension an array. It is particular useful when you
> are likely to encounter an variable length array (different length each
> time the code executes). Normally when the array is re-dimensioned the
> previous values are destroyed because you normally want to enter new
> values into the array. Some flavors of basic allow to use ReDim Preserve
> to preserve the array's original value - you may want to try this to see
> if works.

No, Preserve does the opposite, it preserves all the values. I want an
EMPTY array without having to empty them with a time consuming For
loop, so I though ReDim should do the job very quickly. It does in
most cases, but as my example shows, not always…

As you can see in my example, after ReDim y is reset to 0 (y.a=0,
y.b=0) but x is not (x(0).a=1, for example). The difference between x
and y is that x is an array and x is declared above the subroutine
(this was a couple of days ago, so I don't remember if I tested
absolutely everything, but as far as I remember, my conclusion was
that an array of a custom type isn't reset to 0 after ReDim, I am not
sure if there was a difference if it was defined in a subroutine or
outside.

So my question still is: Is this what I should expect or is it a bug?
If it is a bug I will need to write a bug report, won't I? But I don't
want to do that if this is the expected behaviour, because it only
annoys people…


Kind regards

Johnny Rosenberg
ジョニー・ローゼンバーグ

> A common use is
> Dim MyArray() as type
>
> ReDim MyArry(1 to x), x will be supplied by the procedure.
>
> Often there are little subtleties that can drive you crazy when program,
> the compiler/interpreter is very fussy that you follow all the grammar
> and syntax rules for the langauge.
> --
> Jay Lozier
> jslozier@gmail.com
>
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