On Fri, 9 Jul 1999, Oleg Krivosheev wrote:
> > to not be handled properly. Even though I specify -fpack_struct the
> > generated code does not appear to actually do this. Structure fields
> > are
> > offset and the return from sizeof() returns a value that is not valid.
>
> what do you mean it is not valid? Read ANSI standard or any
> decent C book. It is quite valid - compiler may insert any padding
> between struct members...
He probably means it is not exactly what he wants :>
> > For instance, if the structure were:
> >
> > struct foo {
> > char text[3];
> > int num;
> > };
> >
> > sizeof would return 6 and not 5.
>
> 6? Are you sure you're using Linux/gcc?
Yes, 6, it will insert a single extra character at the end of text to
place the alignment of num on a 4 byte boundry.
> > So it's obvious that the compiler is
> > placing a pad byte between text and num to align num. I want it to
> > stop!
I always hated gcc __attribute__, I prefer the simpler and more common
#pragma pack(1)
struct {};
#pragma pack()
Which forces the layout to be as you specified.
Using a command line option is a Bad Idea (tm) as it may corrupt glibc's
structures
Jason
