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From: gdr11@cl.cam.ac.uk (Gareth Rees)
Subject: Re: ANSI C and POSIX (was Re: C/C++ knocks the crap out of Ada)
Date: 1996/04/12
Message-ID: <yxsag0hel99.fsf@stint.cl.cam.ac.uk>#1/1
X-Deja-AN: 147103657
references: <JSA.96Feb16135027@organon.com> <4kb2j8$an0@solutions.solon.com>
followup-to: comp.lang.c
organization: Cambridge University Computer Lab
newsgroups: comp.lang.ada,comp.lang.c,comp.lang.c++,comp.edu
Date: 1996-04-12T00:00:00+00:00
List-Id: <comp.lang.ada>

Chet <kackman> wrote:
> If i = j depends on your unit of address. If i is assumed a longword then
> 
>      &i + 4 = &j is true
>      not 
>      &i + 1 = &j

In the C language, the `unit of address' in address arithmetic depends
on the type of the address on which the arithmetic happens.  Go back and
read section 5.4 of K&R2 again.

$ uname -sr
SunOS 4.1.3_U1
$ cat arith.c
#include <stdio.h>
int main () {
    int i;
    printf("%p + 1 = %p\n", &i, &i+1);
    return 0;
}
$ gcc arith.c
$ ./a.out
f7fffa3c + 1 = f7fffa40

Followups to comp.lang.c only.

-- 
Gareth Rees