Re: C question

[mayur nande <mayur.nan@gmail.com>]

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Hi Rick,

Some days ago i had the same question in my mind. While going through "The
Linux Kernel Architecture" book (by Wolfgang Mauerer), i got the answer:

The GNU compiler supports arithmetic with void pointers as well as function
pointers. The increment step is 1 byte. These are used by the kernel at
various points.

Have fun.

Regards
Mayur

On Thu, Oct 8, 2009 at 7:42 AM, Rick Brown <rick.brown.3@gmail.com> wrote:

> Hello list,
>
> As far as I recall from K&R, isn't pointer arithmetic on a void
> pointer banned? And any effort to do that results in an error -
> because the compiler won't know by how much size to increment the
> pointer for a statement like "ptr++"? But then how about this:
>
> [rick@linux rick]$ cat t.c
> #include <stdio.h>
> int main()
> {
>    void *ptr = 0;
>    printf("%d \n", ptr+1);
> }
> [rick@linux rick]$ gcc t.c
> [rick@linux rick]$ ./a.out
> 1
> [rick@linux rick]$
>
> It compiles and runs fine ... !
>
> TIA,
>
> Rick
>
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