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From: Mirsad Todorovac
Subject: `Val' function problems
Date: 15 Aug 2003, 11:45:08

On Thu, 14 Aug 2003, Frank Heckenbach wrote:

> Prof A Olowofoyeku (The African Chief) wrote:
> > > Mirsad Todorovac wrote:
> > >
> > > > The other side of the story is that Val could be used more flexible,
> > > > i.e. for parsing if "best effort" has been done, and string has been
> > > > converted-up to the first invalid character/digit.
> > >
> > > We could do that if we decide to interpret it as undefined.
> > >
> > > However, since `Val' is a BP function, anyway, I'd tend to change
> > > GPC's behaviour and set the number to 0. (In the case where you want to
> > > ignore the trailing garbage, it's easy to pass the prefix to `Val'
> > > again.)
> >
> > What Mirsad suggests seems to be what Delphi does (i.e., stop where the
> > error starts, and return what was possible to convert before the error -
> >  but again the Delphi help file does not document this, so I am not
> > sure that one should rely on this behaviour).
>
> Perhaps we should leave it undefined until/unless someone provides a
> reference of clearly documented behaviour of other compilers. (If
> that's what we do, please mention it in the reference, Mirsad.)

I was thinking about how having the sane part of string converted and
stored could provide extra functionality - that would add a means for the
function to be used in i.e. numerical expressions parsing at little extra
cost, since the number appears to be already converted (the right
value appears in `x' in the case of only one invalid char).

Of course, provided that this is what we want. We could OTOH want either
completely 'clean' string or nothing.

I can't tell the number of program's that do rely on BP or Delphi `Val'
undocumented behavior.

Frank?

Mirsad

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