NULL question not in FAQ

[Checkpoint Technologies]

In article <1991Mar26.235643.4498 at ux1.cso.uiuc.edu> phil at ux1.cso.uiuc.edu (Phil Howard KA9WGN) writes:
>Given that the compiler is supposed to translate the constant "0" to the
>appropriate value for a NULL pointer on the machine type, how does one
>get a pointer value whose representation happens to be all zeroes, but
>is a non-NULL pointer?

void some_func(void) {
	int **ip;

	ip = (int **) calloc(sizeof(int *), 1);

	...

And now, *ip is a pointer whose representaiton is all-bits-zero, which
of course is not guaranteed to be NULL, but *probably is on your
implementation.  Most architectures are not capable of distinguishing
between a pointer representation of all-bits-zero, and a null pointer.
But you as a programmer should make this distinction.

And, if I might restate the rest, for brevity...

I am comfortable with the idea that 0 may be transformed into the null
pointer value.  However, the FAQ says that the *compiler* translates
the integer 0 *constant* into the null pointer.  It says nothing about
transforming, at run time, integer zero values which may be in an object.
Therefore, the following is not guaranteed to give me a null pointer:

	int i = 0;
	char *p = (char *)i;

So is it correct to interpret this code as unportable?
--
First comes the logo: C H E C K P O I N T  T E C H N O L O G I E S      / /
                                                ckp at grebyn.com      \\ / /
Then, the disclaimer:  All expressed opinions are, indeed, opinions. \  / o
Now for the witty part:    I'm pink, therefore, I'm spam!             \/