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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: How to write this sign function in Delphi. |
| Date | 2015-09-30 13:04 -0700 |
| Organization | None to speak of |
| Message-ID | <lnoagj3c95.fsf@kst-u.example.com> (permalink) |
| References | (14 earlier) <e9c6eb98-7324-4485-9b34-d004f0d09177@googlegroups.com> <muatrp$8kg$1@dont-email.me> <mub0oi$ije$1@dont-email.me> <mub51i$23e$1@dont-email.me> <muh162$rq5$1@dont-email.me> |
Bartc <bc@freeuk.com> writes:
[...]
> What would you do in this situation: you have an application that runs
> on x86 processors (which was used by a big chunk of the world's desktop
> computers at one point; perhaps it still is). And a client that is
> demanding 64-bit floating point precision [which actually happened to me].
(Richard answered this, but I'll answer it too.)
If the requirement is specifically for 64-bit floating-point, I'd
probably do something like:
int main(int argc, char **argv) {
if (sizeof (double) * CHAR_BIT != 64) {
fprintf(stderr, "Sorry, double is not 64 bits\n");
exit(EXIT_FAILURE);
}
/* Do the actual work here */
}
The error probably won't be triggered on any x86 system. If it is,
I'd have to look into alternatives, perhaps resorting to long double
(though that's not guaranteed to be wider than double).
This assumes the client wants *exactly* 64 bits; change "!=" to "<" if
he'd be satisfied with more than 64 bits.
If the requirements are stated in terms of range and precision, I can do
the check at compile time, using the macros defined in <float.h>. (The
preprocessor doesn't know about `sizeof`.)
If, as is more likely, the client actually wants IEEE (IEC 60559)
floating-point arithmetic, it's a bit easier:
#ifndef __STDC_IEC_559__
#error "IEC 559 is not supported"
#endif
which guarantees that the type double matches the IEC 60559 double
format.
> You've chosen to program in C; what are you going to do: tell the client
> what he wants is not guaranteed by the language so it is not possible?
If the client insists on 100% portable C code, that's exactly what
I'd tell him. If the client is willing to pay for a software IEEE
implementation written in 100% portable C, I might try to talk him
out of it because it's unlikely to be worth the effort -- but it's
possible that's what the customer really needs. (There are probably
existing software implementations out there; I haven't checked.)
If he merely wants 64-bit IEEE floating-point for some particular set of
platforms, or even just one, I wouldn't bother mentioning that it's not
guaranteed by the language, because that wouldn't be relevant.
[...]
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:17 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:43 +0200
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-21 19:51 +0100
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 23:26 +0200
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-21 22:47 +0100
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 16:29 +0200
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-22 16:11 +0100
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-23 11:18 +0200
Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-09-23 13:01 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:53 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:54 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:58 +0200
Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 18:15 -0400
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-21 15:21 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-21 17:51 -0500
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-21 19:15 -0400
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-21 23:59 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 09:22 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-22 10:32 -0700
Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-22 18:17 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 12:25 -0700
Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-22 22:33 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 15:52 -0700
Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-09-22 23:09 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-23 09:07 -0700
Re: How to write this sign function in Delphi. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-09-23 16:55 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-23 10:46 -0700
Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-23 23:18 +0000
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-23 22:29 -0400
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-24 11:09 +0100
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-27 18:23 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 05:20 +0000
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-27 23:23 -0700
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 09:03 +0100
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-28 01:24 -0700
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 09:32 +0100
Re: How to write this sign function in Delphi. Bartc <bc@freeuk.com> - 2015-09-28 10:22 +0100
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 11:35 +0100
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 10:33 -0700
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 18:59 +0100
Re: How to write this sign function in Delphi. Rosario19 <Ros@invalid.invalid> - 2015-09-28 20:09 +0200
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 13:39 -0500
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 20:04 +0100
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:43 -0500
Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-09-28 18:55 -0500
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 19:31 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-28 12:16 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 14:31 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:47 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-29 11:54 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-01 00:36 -0500
Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 10:53 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 09:48 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-03 11:27 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 12:32 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-03 11:26 -0500
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 16:46 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 14:23 -0700
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:52 -0500
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 01:39 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 12:37 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-30 21:28 +0000
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-30 17:54 -0400
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-01 03:59 +0000
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-01 01:42 -0400
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 16:20 -0700
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 16:39 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 23:23 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-29 09:35 -0700
Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 11:06 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 09:23 -0700
Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-10-02 12:07 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 10:47 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-02 17:48 -0700
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-10-03 16:46 +0100
Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-10-05 10:41 -0500
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-28 15:31 -0400
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:40 -0500
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-28 18:17 -0400
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 02:49 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-30 06:27 -0700
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-29 10:43 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 22:51 +0000
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 02:11 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 22:48 +0000
Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 22:03 -0500
Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 01:13 -0700
Re: How to write this sign function in Delphi. Bartc <bc@freeuk.com> - 2015-09-30 17:06 +0100
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-30 17:26 +0100
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 13:04 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 09:12 +0000
Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-09-28 12:28 +0200
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-28 20:44 +0100
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-01 01:39 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-01 08:55 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-01 09:02 -0700
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-01 14:55 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-01 16:48 -0700
Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 11:46 +0000
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-06 00:15 -0700
Re: How to write this sign function in Delphi. Les Cargill <lcargill99@comcast.com> - 2015-10-06 02:43 -0500
Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-10-06 10:13 +0200
Re: How to write this sign function in Delphi. Les Cargill <lcargill99@comcast.com> - 2015-10-06 19:14 -0500
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 21:36 -0700
Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-06 09:25 +0100
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 09:28 -0700
Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-06 13:11 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 13:56 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-07 00:25 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 09:44 -0700
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-06 10:08 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 12:00 -0700
Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-07 01:58 -0700
Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-10-07 10:12 +0100
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-08 00:40 -0700
Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:29 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 13:20 -0700
Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:33 -0700
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-03 17:02 -0400
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 15:04 -0700
Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-04 05:12 +0000
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-04 12:58 -0700
Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:37 -0700
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-03 16:21 -0400
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 16:05 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 14:02 -0700
Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-24 09:39 -0700
Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-09-27 16:26 +0000
Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 22:06 -0400
Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-22 10:17 -0400
Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-22 19:48 -0400
Re: How to write this sign function in Delphi. Noob <root@127.0.0.1> - 2015-09-23 13:15 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:25 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:54 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 22:02 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:50 +0200
Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 18:08 -0400
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 08:31 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 10:18 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 10:50 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:00 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:07 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:20 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:15 +0200
Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:23 +0200
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