Invalid Pointers

[Doug Gwyn]

In article <4348 at eos.UUCP> jbm at eos.UUCP (Jeffrey Mulligan) writes:
-It has been pointed out that there should be no assumptions
-about what addresses are valid; is there any way to get
-a guaranteed INVALID address?

A null pointer is guaranteed not to match any valid object address.

-#define NO_FOOBAR ((struct foobar *) -1 )	is what I use, but...

This is not portable.  Just use NULL.