Portability questions (Arrays)_(re)

Thu, 8 May 1997 02:10:58 +0200

Now, after Peter's and Berend's answers I'm a bit confused...
Could someone clear things up for me, please?

Note, I'm talking about gpc, not about other compilers or about the standard.

Peter Gerwinski wrote:

> Why is this so, e.g. with an array of something which has 3 bytes?
>
>
>     Program Test;
>
>     Type
>       r = packed record
>         x: ShortWord;
>         y: Byte;
>       end (* r *);
>
>     Var
>       x: packed array [ 1..1000 ] of r;
>
>     begin
>       writeln ( SizeOf ( x ) );
>       writeln ( SizeOf ( x [ 1 ] ) );
>     end.
>
>
> The output is 4000 and ... 4.  To avoid alignment problems in an "array
> of r", the record `r' has size 4, not 3.

BTW: Does this mean if you have

var
  a:r;
  b:byte;

then 1 byte after a will be "wasted" though b could fit into it? It has to be
so if sizeof(a)=4, if someone does "move(...,a,sizeof(a))".
-- 
Frank Heckenbach, Erlangen, Germany
heckenb@mi.uni-erlangen.de
Turbo Pascal:   http://www.mi.uni-erlangen.de/~heckenb/programs.htm
Internet links: http://www.mi.uni-erlangen.de/~heckenb/links.htm

Frank Heckenbach (heckenb@mi.uni-erlangen.de)