From:	Robert Hoehne <Robert DOT Hoehne AT Mathematik DOT TU-Chemnitz DOT DE>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: GCC/Info docs bug regarding __attribute__
Date:	Fri, 01 Aug 1997 12:53:05 +0200
Organization:	TU Chemnitz-Zwickau
Lines:	45
Message-ID:	<33E1C011.4A51DB09@Mathematik.TU-Chemnitz.DE>
References:	<5rrni2$48j AT freenet-news DOT carleton DOT ca>
NNTP-Posting-Host:	prokyon.hrz.tu-chemnitz.de
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Paul Derbyshire wrote:
> 
> In a program I am writing I am having problems using __attribute__ ((packed))
> on a struct meant for reading the (unpacked) records of a binary file

DJGPP comes with a very good example of how to use this attribute.
Look at the include/dos.h file how the struct _fint_t is declared.

BTW: There you can see, that you have to "pack" each element of the
struct and not only the struct at once.

> I am forced to conclude one of three things is the case:


Here my guess about your problem:

You are using it in a C++ file?? (please include that information
in the furure, because C and C++ are sometimes different to program).

The description in the gcc docs are valid only for C and not for C++.
(I tried it now).

Here is the syntax, which can be used in both languages

typedef struct
{
  char dummy2
  char dummy2;
} foo __attribute__ ((packed));

But as said above this will not solve you problem, because
you have to pack EACH member of the struct.


BTW: All the above is nowhere written, I found it only
by trying it many times ago.

Robert
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* Robert Hoehne, Fakultaet fuer Mathematik, TU-Chemnitz-Zwickau *
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