Invalid Pointers

[Doug Gwyn]

In article <8990 at chinet.chi.il.us> les at chinet.chi.il.us (Leslie Mikesell) writes:
-In article <10541 at smoke.BRL.MIL> gwyn at brl.arpa (Doug Gwyn) writes:
->>#define NO_FOOBAR ((struct foobar *) -1 )	is what I use, but...
->This is not portable.  Just use NULL.
-Do you mean that there are machines that might return a valid -1 from
-sbrk(2) or shmat(2), or that would misconstrue the comparsion of
-a pointer to -1?

What I mean is what I said.

-Yes, I know these are botches, but are they not always accomodated?

No.  Non-UNIX systems need not even try to accommodate them.