ANSI C, hardware protection, out-of-bounds pointers

[Joseph S. D. Yao]

In article <427 at maytag.waterloo.edu> lhf at aries5 (Luiz H. deFigueiredo) writes:
-ANSI C says that is *is* legal to use mention (but not dereference) a pointer
-just out-of-bounds as in
-
-	char a[N];
-	char *last=a+N;		/* Here! */
-	char *p;
-	for (p=a; p<last; p++)
-Now I ask, it is possible/legal to do the analogous thing for a-1 as in
-	char *head=a-1;		/* Here! */
-	for (p=last-1; p>head; p--)

This, too, is an out-of-bounds pointer, and is covered by the same
rule.  Nothing says that an OOB ptr has to be positively offset.

joe yao