Re: A curiosity...

[Keith Thompson <kst-u@mib.org>]

Samuel Tardieu <sam@rfc1149.net> writes:
>>>>>> "Ludovic" == Ludovic Brenta <ludovic@ludovic-brenta.org> writes:
> Ludovic> And I think this rule is responsible for the "limitation"
> Ludovic> that all current processor architectures use addresses which
> Ludovic> are the same size as integers. Before the advent of C,
> Ludovic> address size and word size were not necessarily the same; now
> Ludovic> they always are, and that's *only* for compatibility with C.
>
> Certainly not. For example, on a x86_64 Linux machine with GCC, you
> can try the following snippet (untested):
>
> #include <stdio.h>
> int main()
> {
>   printf("integer size is %d, pointer size is %d\n",
>          sizeof(int), sizeof(void*));
>   return 0;
> }
>
> You should get respectively 4 and 8.
[...]

You get undefined behavior, since "%d" expects an argument of type int
and you're giving it an argument of type size_t.  And on the system in
question, it's very likely that size_t is bigger than int, so this
could cause real problems.

    printf("integer size is %lu, pointer size is %lu\n",
           (unsigned long)sizeof(int), (unsigned long)sizeof(void*));

or, in C99:

    printf("integer size is %zu, pointer size is %zu\n",
           sizeof(int), sizeof(void*));

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
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