argv[] terminated by a NULL pointer?

[David Brooks]

djimenez at ringer.cs.utsa.edu (Daniel Jimenez) writes:
|> Who said the null pointer couldn't be -1?

Who's allowed to know?

|> On a system where the null pointer is represented by all bits one,
|> the following statement:
|> ((char *)0) == ((char *)-1) 
|> would be true, since 0 in a pointer context is defined to be
|> the null pointer, and -1 is also the null pointer.
|> They would have the same bit pattern.

Is this strictly true?  I know that the conversion of an *object* of
integral type is allowed to go through an implementation-dependent mapping,
although K&RII (at least) doesn't seem to mention an integer constant.

It would be rather perverse to map (char *)-1 to 0x8129ac60, but I could
imagine a compiler writer wanting to avoid mapping -1 to a value internally
identical to a null pointer.
-- 
David Brooks				dbrooks at osf.org
Systems Engineering, OSF		uunet!osf.org!dbrooks
Composing for a percussion ensemble is like writing an essay in highlighter.