On Mon, 23 Nov 2015 06:45:54 -0500
Hendrik Boom <hendrik@???> wrote:


> There is a well-known hack in C wheereby you rely on C allocating
> fields of structures independently of later fields.
>
> Thus with
> struct foo{char c, int d, float e,}
> and
> struct bar{char c, int d,}
>
> (forgive me if I need semicolons here; I've used too many languages
> in the alst year to remember the surface syntax)
>
> you can rely on c and d having the same offsets in both structures,
> and so you can happily cast between pointers to foo and bar as long
> as you don't mess with e.
>
> And, of course, you can have a pointer to a table of methods as the
> first entry in all of these structures.

Aren't C unions the "official" way to deal with these situations?

SteveT

Steve Litt 
November 2015 featured book: Troubleshooting Techniques
     of the Successful Technologist
http://www.troubleshooters.com/techniques