Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #153382
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Are bitfields useful? |
| Date | 2020-07-30 18:08 -0700 |
| Organization | None to speak of |
| Message-ID | <87zh7ga3tn.fsf@nosuchdomain.example.com> (permalink) |
| References | <6bcaccac-13ef-45cd-bbc7-0dbd5d452f68o@googlegroups.com> <rfvjgv$3f9$1@dont-email.me> <6VJUG.737545$f44.615001@fx09.am4> |
Bart <bc@freeuk.com> writes:
[...]
> So, what are the rules that will let me predict those results? For
> example because I need to create a duplicate struct from another
> language. Because I can't figure it out.
>
>
> ----------------------------
> typedef struct {
> int a:1;
> int b:7;
> } s1;
>
> typedef struct {
> char a:1;
> char b:7;
> } s2;
>
> typedef struct {
> short a:9;
> char b:7;
> } s3;
>
> #include <stdio.h>
>
> int main(void) {
> printf("%d %d %d\n",(int)sizeof(s1),(int)sizeof(s2),
> (int)sizeof(s3));
> }
Keep in mind that support for bit-fields of types other than
_Bool, signed int, or unsigned int is implementation-defined.
(A bit-field of type int is treated as signed int or unsigned int;
the choice is implementation-defined.)
Most aspects of bit-field layout are implementation-defined.
See N1570 6.7.2p11 for the details. So the rules should be in the
documentation for whatever implementation you're using.
--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Are bitfields useful? Frederick Gotham <cauldwell.thomas@gmail.com> - 2020-07-30 02:10 -0700
Re: Are bitfields useful? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-07-30 09:50 +0000
Re: Are bitfields useful? jacobnavia <jacob@jacob.remcomp.fr> - 2020-07-30 12:18 +0200
Re: Are bitfields useful? Frederick Gotham <cauldwell.thomas@gmail.com> - 2020-07-30 04:01 -0700
Re: Are bitfields useful? David Brown <david.brown@hesbynett.no> - 2020-08-03 12:26 +0200
Re: Are bitfields useful? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-07-30 03:10 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-30 12:11 +0100
Re: Are bitfields useful? Richard Damon <Richard@Damon-Family.org> - 2020-07-30 07:54 -0400
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-30 13:14 +0100
Re: Are bitfields useful? Richard Damon <Richard@Damon-Family.org> - 2020-07-30 21:18 -0400
Re: Are bitfields useful? jadill33@gmail.com - 2020-07-30 09:57 -0700
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-30 18:37 -0400
Re: Are bitfields useful? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2020-07-30 19:15 -0400
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-30 20:36 -0400
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-30 19:01 -0400
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 01:49 +0100
Re: Are bitfields useful? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-07-30 18:08 -0700
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-30 19:28 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 11:15 +0100
Re: Are bitfields useful? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-07-31 11:47 +0000
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 05:00 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 13:53 +0100
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 07:59 -0700
Re: Are bitfields useful? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2020-07-31 11:32 -0400
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 13:55 -0400
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 17:30 +0100
Re: Are bitfields useful? scott@slp53.sl.home (Scott Lurndal) - 2020-07-31 17:59 +0000
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 11:19 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 20:54 +0100
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 15:14 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-08-01 00:31 +0100
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 16:55 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-08-01 01:16 +0100
Re: Are bitfields useful? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-07-31 20:31 -0700
Re: Are bitfields useful? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-07-31 12:55 -0700
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 21:04 +0100
Re: Are bitfields useful? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-08-23 16:16 -0700
Re: Are bitfields useful? Richard Damon <Richard@Damon-Family.org> - 2020-07-31 08:23 -0400
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-07-31 14:20 +0100
Re: Are bitfields useful? Philipp Klaus Krause <pkk@spth.de> - 2020-08-04 17:21 +0200
Re: Are bitfields useful? Kaz Kylheku <793-849-0957@kylheku.com> - 2020-08-25 00:13 +0000
Re: Are bitfields useful? Bart <bc@freeuk.com> - 2020-08-25 12:42 +0100
Re: Are bitfields useful? scott@slp53.sl.home (Scott Lurndal) - 2020-08-25 15:27 +0000
Re: Are bitfields useful? Kaz Kylheku <793-849-0957@kylheku.com> - 2020-08-25 16:05 +0000
Re: Are bitfields useful? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-07-30 17:26 -0700
Re: Are bitfields useful? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2020-07-31 22:32 -0700
Re: Are bitfields useful? Richard Damon <Richard@Damon-Family.org> - 2020-08-01 10:20 -0400
Re: Are bitfields useful? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-08-23 07:54 -0700
Re: Are bitfields useful? Kaz Kylheku <793-849-0957@kylheku.com> - 2020-08-25 00:26 +0000
Re: Are bitfields useful? Kaz Kylheku <793-849-0957@kylheku.com> - 2020-08-25 23:55 +0000
csiph-web