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| Subject | Re: Portable 16 bit binary integer write |
|---|---|
| Newsgroups | comp.lang.c |
| References | <50a1e8f4-4fb3-4491-97d0-54768bf28685@googlegroups.com> |
| From | Richard Damon <Richard@Damon-Family.org> |
| Message-ID | <OtSBz.4346$g01.3583@fx33.iad> (permalink) |
| Organization | Forte - www.forteinc.com |
| Date | 2016-09-13 08:41 -0400 |
On 9/10/16 5:23 PM, Malcolm McLean wrote:
> Is this bullet-proof?
> Write a two's complement 16-bit integer in binary format, regardless of host
> integer encoding.
>
> int fput16be(int x, FILE *fp)
> {
> unsigned int rack;
> int answer;
>
> assert(x >= -32678 && x < 32768);
>
> if (x >= 0)
> rack = x;
> else
> {
> if (x == -32768)
> rack = 0xFFFF;
> else
> {
> rack = -x;
> rack = ~rack;
> rack++;
> }
> }
> fputc((rack >> 8) & 0xFF, fp);
> answer = fputc(rack & 0xFF, fp);
> return answer;
> }
>
> What is the best strategy on x out of range or fputc returning EOF?
>
First, you don't need all the complicated conversion unless you are
trying to handle a non-compliant implementation (and then the standard
can't be of help).
The conversion of a signed to an unsigned is ALWAYS to be done via
modular arithmetic, so
unsigned int rack = -1;
rack &= 0xFFFF;
must put the value of 65535 (0xFFFF) into rack, and similarly for other
negative numbers. If you are willing to depend on unt16_t existing, you
can remove the &= operation.
As to what to do on errors, that depends a LOT on your own goals.
Sometimes the best thing to do is do as best you can to push through. In
that case rather than assert, just take the bottom 16 bits of the value
and output that, and have let the user check the stream status for
errors at the end. Other cases you might want the function to return an
error value on out of bounds parameters and not do anything (in which
case you may want to also check the first fputc for and error too). Some
cases may want the assert like you have (which will fault in debug, and
just plow through in production assuming you build production with
asserts disabled).
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Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-10 14:23 -0700
Re: Portable 16 bit binary integer write Barry Schwarz <schwarzb@dqel.com> - 2016-09-10 17:11 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-11 07:00 -0700
Re: Portable 16 bit binary integer write Richard Damon <Richard@Damon-Family.org> - 2016-09-13 08:41 -0400
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-13 06:24 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-13 16:19 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-13 10:20 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-13 11:07 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-13 20:47 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-14 08:24 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-15 12:17 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-15 11:27 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-15 09:03 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-15 11:21 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-15 18:39 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-15 12:26 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-15 23:12 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-15 16:17 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-15 18:35 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-16 11:10 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-16 08:43 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-16 19:59 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-16 13:34 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-16 16:23 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-16 15:31 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-16 19:06 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-16 23:27 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-17 15:04 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-17 20:35 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 00:09 -0700
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-18 19:36 +0100
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 15:29 -0700
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-19 01:20 +0100
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-18 09:48 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-18 19:38 +0200
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-18 15:33 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-18 13:58 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-18 14:15 -0700
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-18 23:15 +0100
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-18 15:46 -0700
Re: Portable 16 bit binary integer write Ian Collins <ian-news@hotmail.com> - 2016-09-19 17:03 +1200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-19 07:40 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 10:54 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 10:51 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 22:03 +0200
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 15:44 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-20 09:02 +0200
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-19 21:12 +0100
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 15:58 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 09:49 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-19 02:37 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 13:20 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-19 06:22 -0700
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-19 12:46 +0100
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 16:20 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-19 07:32 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 11:26 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-19 09:10 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-19 09:33 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-19 11:54 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 22:14 +0200
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-19 22:12 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-19 14:32 -0700
Re: Portable 16 bit binary integer write Robert Wessel <robertwessel2@yahoo.com> - 2016-09-19 22:58 -0500
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-20 09:45 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-20 07:49 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-20 19:43 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-20 11:15 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-19 22:36 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-22 21:30 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-22 23:58 -0700
Re: Portable 16 bit binary integer write Ian Collins <ian-news@hotmail.com> - 2016-09-23 19:45 +1200
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 08:17 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-28 09:59 -0700
Re: Portable 16 bit binary integer write Ian Collins <ian-news@hotmail.com> - 2016-09-29 07:59 +1300
Re: Portable 16 bit binary integer write Ike Naar <ike@iceland.freeshell.org> - 2016-09-28 19:26 +0000
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-28 12:37 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-10-09 03:46 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-18 13:53 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-21 21:03 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-21 22:23 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-22 08:09 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 10:31 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-23 10:56 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-29 08:03 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-30 07:39 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-22 09:49 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-22 08:34 -0700
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-22 17:44 +0100
Re: Portable 16 bit binary integer write Melzzzzz <Melzzzzz@zzzzz.com> - 2016-09-22 17:16 +0000
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-22 18:26 +0100
Re: Portable 16 bit binary integer write Melzzzzz <Melzzzzz@zzzzz.com> - 2016-09-22 17:33 +0000
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-23 10:23 +0200
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-23 13:43 +0100
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-23 14:58 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-22 18:14 -0700
Re: Portable 16 bit binary integer write luser droog <luser.droog@gmail.com> - 2016-09-22 20:28 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-23 00:12 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-22 10:57 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-23 10:18 +0200
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 11:48 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-23 15:58 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-29 08:21 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-30 07:42 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-23 23:38 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-24 11:42 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-24 14:13 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-24 23:03 -0700
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-25 11:29 +0100
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 14:02 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-25 15:17 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 16:52 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 13:59 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-25 15:13 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 15:50 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 08:13 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-24 16:06 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-24 11:53 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-24 14:23 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 14:16 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-25 15:18 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-25 16:39 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-25 23:33 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-26 02:08 -0700
Re: Portable 16 bit binary integer write Richard Heathfield <rjh@cpax.org.uk> - 2016-09-26 10:25 +0100
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-26 03:05 -0700
Re: Portable 16 bit binary integer write Richard Heathfield <rjh@cpax.org.uk> - 2016-09-26 11:09 +0100
Re: Portable 16 bit binary integer write "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-09-26 09:29 -0700
Re: Portable 16 bit binary integer write Richard Heathfield <rjh@cpax.org.uk> - 2016-09-26 17:37 +0100
Re: Portable 16 bit binary integer write "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-09-26 12:29 -0700
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-26 11:12 +0100
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-26 13:19 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-26 18:34 -0700
Re: Portable 16 bit binary integer write Ike Naar <ike@iceland.freeshell.org> - 2016-09-27 06:43 +0000
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-27 00:51 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-27 08:42 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-22 11:40 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 10:00 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-23 10:34 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-29 08:13 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-18 00:06 +0200
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-17 17:32 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-18 15:57 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-17 20:46 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-18 16:08 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-18 10:03 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-17 23:59 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-17 16:49 -0700
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-18 01:19 +0100
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-18 07:16 -0700
Re: Portable 16 bit binary integer write "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-18 10:19 -0400
Re: Portable 16 bit binary integer write luser droog <luser.droog@gmail.com> - 2016-09-18 13:26 -0700
Re: Portable 16 bit binary integer write "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-18 17:04 -0400
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-22 01:21 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-15 12:07 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-16 00:32 +0200
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-15 16:30 -0700
Re: Portable 16 bit binary integer write Keith Thompson <kst-u@mib.org> - 2016-09-15 18:35 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-15 22:00 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-15 22:17 -0700
Re: Portable 16 bit binary integer write Ian Collins <ian-news@hotmail.com> - 2016-09-16 18:12 +1200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-16 00:46 -0700
Re: Portable 16 bit binary integer write Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-16 10:23 +0100
Re: Portable 16 bit binary integer write BartC <bc@freeuk.com> - 2016-09-16 10:59 +0100
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-16 04:13 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-16 08:58 -0700
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-16 10:16 -0700
Re: Portable 16 bit binary integer write Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-16 09:11 -0700
Re: Portable 16 bit binary integer write David Brown <david.brown@hesbynett.no> - 2016-09-16 20:14 +0200
Re: Portable 16 bit binary integer write Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-16 20:37 -0700
Re: Portable 16 bit binary integer write supercat@casperkitty.com - 2016-09-13 07:47 -0700
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