Re: [libreoffice-users] Is there any way to prevent LibreOffice BASIC to convert types automatically?

2011/8/17 Clio <menenem@bk.ru>:
> 17.08.2011 16:15, Johnny Rosenberg пишет:
> > I have an issue where I get error messages for type mismatch sometimes
> > and sometimes not. After a lot of debugging I found the reason.
> >
> > The code looks like this, kind of:
> >
> > Public CatPoints(1 To 20) As Integer
> >
> >
> > Sub Something
> > ⁝
> > Dim Points(13) As Integer
> > ⁝
> > Dim i As Integer
> > ⁝
> > For i=7 To 20
> > CatPoints(i)=Iif(MaxiPlayerCategory(i),-1,Points(i-7)) ' An type
> > mismatch error sometimes occurs here.
> > ⁝
> > Next i
> > ⁝
> > End Sub
> >
> >
> > Function MaxiPlayerCategory() As Boolean
> > ⁝
> > End Function
> >
> > The MaxiPlayerCategory function works fine and returns True or False
> > depending on external things, in this case it returns False, which
> > means that Points(i-7) is returned by the Iif statement.
> >
> > So after debugging for quite a while I noticed that the Points()'
> > array changes its type to double for some elements, so some of them
> > remains Integer and a few of them are suddenly Double!
> > Why is that? Well, because the elements of Points() are calculated
> > differently depending on some stuff that is not important. Some of the
> > elements are calculated by functions and some are calculated directly,
> > something like Points(7)=3*something+2*somethingElse.
> >
> > So when something is just calculated the return value of the operation
> > seems to be Double no matter what, and arrays seems to adopt to that
> > automatically.
> > Of course I can correct this like this:
> > Points(7)=CInt(3*something+2*somethingElse).
> >
> > But some of my lines are long enough already and I want compact code
> > if possible, so my question now is:
> > Is there some way I can define/declare an array making it to refuse to
> > change type of its elements? That is, something that makes the return
> > value of an operation automatically converted to an Integer or that
> > forces the operation to stay Integer?
> >
> >
> > By the way, isn't it strange that
> > ”Points(7)=3*something+2*somethingElse” makes Points() change the type
> > of an element while
> > ”CatPoints(i)=Iif(MaxiPlayerCategory(i),-1,Points(i-7))” produce an
> > error message instead? Both CatPoints() and Points() are declared the
> > same way, except that CatPoints() is public to all modules.
> >
> > I also noticed that automatic type conversion occurs when mixing
> > Integers with Strings:
> > Sub Main
> > Dim x As Integer
> > Dim y As String
> >
> > x=10
> > y=LTrim(Str(x)) ' y="10".
> > y=x ' y="10". This one is faster than the other one too.
> > End Sub
> >
> > Haven't tried with Doubles, but I guess that works too.
> > Also the other way around works:
> > Sub Main
> > Dim x As Integer
> > Dim y As String
> >
> > y="10"
> > x=Val(y) ' x=10.
> > x=y ' x=10.
> > End Sub
> >
> >
> >
> > Kind regards
> >
> > Johnny Rosenberg
> > ジョニー・ローゼンバーグ
> This code works fine in LibO3.4.2, OOo3.3.0, Go-OO3.2.1, too:
>
> Sub main
> msgbox 2 + "  " + cStr(10) ' =12
> End Sub
>
> vartype() function still gives different results for x and y in the
> examples. Maybe the types are converted automatically in some cases if type
> mismatch happens? If this happens you don't get any error messages and all
> works as if there were no errors.

Well, my experiments indicates that as soon as there is a mathematical
operation going on (+, -, *, /, ^, math functions), the result is a
Double.
If I do them in a function and the function returns an Integer, the
return value is of course an Integer, which means that the return
value is converted automatically to Integer when the function return
the value.

In my little project I solved it by putting every operation within a
CInt(). The conversion will probably take some time, but probably not
more time than a function return takes to convert to an Integer, if
Integer is its return value.

I remember the 1980's when I played with an ABC80 computer. I remember
that everytime I only need integers, you could force it to keep to
integers, which was two bytes instead of five I think, making the
programs quite a lot faster. But in this case that is not possible. As
far as I'm calculating, a type conversion occurs and then I have to
convert it back again. No speed advantage there, I guess. Maybe
keeping to Double is faster, I haven't done any speed tests in that
matter. Yet…

I wish there was a way to indicate that numbers are Doubles or
Integers. In the old days I did that with %: i%=i%+1% was faster than
i=i+1
I tried that here, but the result was still converted to Double. I am
not sure why, because it's not really needed as long as we only use
integers and as long as we don't divide.


Kind regards

Johnny Rosenberg
ジョニー・ローゼンバーグ

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