Re: struct and members addresses

["Andrea 'fwyzard' Bocci" <fwyzard-gcc at libero dot it>]

At 13.00 24/04/2003 +0100, Cédric Lucantis wrote:
> Hello
>
>    I would like to know if I can assume that a structure and its first member
> will always have the same address. For instance, with the following code:
>
> /* ----------------------------------*/
>
> struct foo
> {
>    any_type    first_member;
> };
>
> struct foo my_struct;
>
> void * addr1 = &my_struct;
> void * addr2 = &my_struct.first_member;
>
> /* ----------------------------------*/
>
> can I be sure that `addr1' will be equal to `addr2' ?
>
> thanks

I think so.
IF yours is a simple struct, ie. no hereditaritey or any C++ thing.

You can check that offsetof (my_struct, first_member) is 0.

.fwyzard.