Re: passing numeric data

["Peter Dow" <pcdow@xxxxxxxxx>]

Hi Scott,

I haven't used pointers much, but from what I've heard (your example
notwithstanding), it's much easier to trash data unintentionally with
pointers than otherwise. What kind of protection is there for pointer usage?
Presumably I can't set a data pointer to a procedure pointer, right? But
what about basing a 32767 byte field on a pointer, then pointing it to a
1-byte field?

Curious,
Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax

From: Scott Klement <klemscot@klements.com>
> The reason that I used pointers is because I'm paranoid about writing data
> to an area of memory outside the scope of my variable.
>
> In the data structure example you give here, if I were to pass a PACKED
> parameter it'd be only 4 bytes long.   If I were to do this:
>
>        c                   MOVE  *ZEROS            PARM1
>
> 3 zeroes would be put into whatever happened to be in the area of memory
> that comes after my parameter.   This can cause all sorts of nasty and
> hard to debug errors.
>
> Whereas, the way I was doing it, this can't happen.   Worst case scenario,
> you'd try to use a field thats still based on a *NULL pointer, which the
> system would know is invalid and it could stop your program with an error.
>
> Granted, if your careful, it won't matter.  :)   I have to wonder why you
> say "why bother with pointers?".  IMHO, pointers arent any more of a
> bother than data structures are.
>
>
>
> On Wed, 8 Mar 2000, Sims, Ken wrote:
>
> > Hi Scott -
> >
> > Why bother with pointers?
> >
> >      d parm1           ds             7
> >      d  zoned1                 1      7s 0
> >      d  packed1                1      4p 0
> >      d*
> >      d myparm1         s              7  0
> >      c*
> >      c     *entry        plist
> >      c                   parm                    parm1
> >      c*
> >      c                   if        %subst(parm1:1:1) >= '0'
> >      c                   eval      myparm1 = zoned1
> >      c                   else
> >      c                   eval      myparm1 = packed1
> >      c                   endif
> >
> > Ken
> > Southern Wine and Spirits of Nevada, Inc.
> > Opinions expressed are my own and do not necessarily represent the views
of
> > my employer or anyone in their right mind.
> >
> >
>
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