In message <Pine.NEB.4.21.9912181313200.12456-100000@shark.int.duh.org>, Todd V
ierling writes:
>However, ptrdiff_t is defined to be an integer the size of a pointer,

No, just big enough to represent the largest difference between parts of a
*single object*.   The implementor can refuse to create objects past a certain
size.

On most implementations, this works, but the Correct Thing To Do is wait for
C9X, test for intptr_t, and if it's not there, commit ritual suicide for
having contaminated yourself with the heresy that pointers are just a special
kind of integer.

-s