Re: add to *Null pointer does not throw an exception.

Hi Joe,

Your results tend to indicate Jim Langston is correct, but a further test is
in order.

 c                   eval      pBase = *null
 c                   eval      pData = pBase + 32
 c                   eval      pData = *null

If pData at this point is showing

 eval pDataDS:x   00000    00000000 00000000 00000000 00000000

then setting a pointer to *null does indeed set it to zero.  Also, if I'm
not mistaken, the high order bits indicate whether it's a valid pointer or
not.  On the other hand, if it shows

 eval pDataDS:x   00000    00000000 00000000 00000000 00000020

then I'd say setting a pointer to *null simply sets bits to invalidate it.
In any case, I agree with Jim that until you use a pointer, its value
doesn't matter.

Still curious,
Peter Dow
Dow Software Services, Inc.
909 793-9050 voice
909 522-3214 cellular
909 793-4480 fax






----- Original Message -----
From: "Joe Pluta" <joepluta@PlutaBrothers.com>
Sent: Monday, October 14, 2002 10:00 PM
Subject: RE: add to *Null pointer does not throw an exception.


> Interesting results.  I had to mess with it a bit:
>
> d pBaseDS         ds
> d pBase                           *
> d pDataDS         ds
> d pData                           *
>
> c                   eval      pBase = *null
> c                   eval      pData = pBase + 32
> c                   eval      *inlr = '1'
> c                   return
>
> I got the following results:
>
> eval pBase       PBASE = SPP:*NULL
> eval pData       PDATA = SPP:*NULL
> eval pBaseDS:x   00000    00000000 00000000 00000000 00000000
> eval pDataDS:x   00000    AF000000 00000000 00000000 00000020
>
> I don't have a clue what this means.  Just thought I'd share it.