What C compilers have non-zero null pointers?

[Henry Spencer]

In article <422 at minya.UUCP> jc at minya.UUCP (John Chambers) writes:
>Consider that the C bible (page 192) says, concerning assignments
>to/from pointers and other types, "The assignment is a pure copy
>operation, with no conversion."  This means that in:
>	int i;
>	char*p;
>	i = 0;
>	p = i;
>the value assigned to p is the same bit pattern as i...

Reading the Old Testament (K&R1) and trying to apply it to modern C is
a mistake.  This code isn't even legal nowadays.  You need an explicit
cast to turn the int into a pointer, and there is no promise that that
cast doesn't do some sort of arcane conversion operation.

Actually, even the Old Testament continued with:  "This usage is
nonportable, and may produce pointers which cause addressing exceptions
when used.  However, it is guaranteed that assignment of the *constant*
0 to a pointer will produce a null pointer distinguishable from a
pointer to any object." [emphasis added]

The constant 0 in a pointer context has no relationship whatsoever to
the integer value 0; it is a funny way of asking for the null pointer,
which need not resemble the int value 0 in any way.
-- 
NFS is a wonderful advance:  a Unix    | Henry Spencer at U of Toronto Zoology
filesystem with MSDOS semantics. :-(   |  henry at zoo.toronto.edu   utzoo!henry