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| From | jacob navia <jacob@spamsink.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: hexump.c |
| Date | 2011-09-11 00:10 +0200 |
| Organization | lccwin |
| Message-ID | <j4gn98$878$1@speranza.aioe.org> (permalink) |
| References | <j4ducg$lmn$1@speranza.aioe.org> <j4ff5i$st9$1@speranza.aioe.org> <op.v1l3n5um5qv6o3@toshiba-laptop> |
Le 10/09/11 23:37, Morris Keesan a écrit :
> On Sat, 10 Sep 2011 06:46:09 -0400, jacob navia <jacob@spamsink.net> wrote:
>
>
>> 18 char tab[16+1];
> ...
>> 24 memset(tab,'.',16);
> ...
>> 34 if (column == 16) {
> ...
>> 40 if (line == 16) {
> ...
>> 52 while (column < 16) {
> ...
>> 57 tab[16]=0;
>
> I usually deduct points from students who use uncommented bare magic
> numbers like this. Especially when the program is related to
> base-16 (hexadecimal) output, and where the 16 in line 40 seems to be
> unrelated to any of the other 16s. This might be a good time to
> introduce the sizeof operator, and/or #defines.
That's what the exercise 4 should learn to do:
4: Add another option (call it -column:XXX) todisplay more or less
text positions in a line. For instance -column:80 would fix the
display to 80 columns. Adjust the number of characters displayed
accordingly. Note that you should not make the number of characters
less than 4 or greater than 512.
The goal here is to show exactly why those magic numbers aren't OK. I
said that in my original post when I started this thread:
<quote>
Note that the manifest
constants will be replaced by #defines in the exercises, when they
are asked to increase the number of columns, etc.
<end quote>
>
>> 6: What would happen if you are working in a machine where the
>> characters are 16 bits wide? What needs to be changed in the
>> above program?
>
> What about if you are working with a machine where the character width
> is not a multiple of 4 bits?
Ahh the famous Deathstation 9000 you mean?
Let's be realistic, maybe those systems existed in the past but now...
> (For many years, I worked with a Unix platform where the chars were
> ten bits wide. Someone doing hardware design thought this was a good
> idea.)
>
Well, I think you would need another exercise for that :-)
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hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 22:53 +0200
Re: hexump.c tea strainer <nospam@nospam.com> - 2011-09-09 21:06 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 23:57 +0200
Re: hexump.c NicStevens <nic.stevens@gmail.com> - 2011-09-12 13:22 -0700
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-10 09:18 +1200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-09 23:59 +0200
Re: hexump.c Ike Naar <ike@iceland.freeshell.org> - 2011-09-09 22:29 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 00:39 +0200
Re: hexump.c Ike Naar <ike@iceland.freeshell.org> - 2011-09-09 22:53 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 00:58 +0200
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-13 06:44 +0000
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-13 10:33 +0200
Re: hexump.c Fritz Wuehler <fritz@spamexpire-201109.rodent.frell.theremailer.net> - 2011-09-13 18:02 +0200
Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-13 16:36 -0400
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-13 22:44 +0200
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 13:31 +0100
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 15:27 +0200
Re: Teaching C (was Re: hexump.c) Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-14 11:49 -0400
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 13:27 -0700
Re: Teaching C (was Re: hexump.c) pacman@kosh.dhis.org (Alan Curry) - 2011-09-14 20:59 +0000
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 22:20 +0100
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-14 17:20 -0400
Re: Teaching C (was Re: hexump.c) pacman@kosh.dhis.org (Alan Curry) - 2011-09-15 01:51 +0000
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 19:29 -0700
Re: Teaching C (was Re: hexump.c) Keith Thompson <kst-u@mib.org> - 2011-09-14 19:21 -0700
Re: Teaching C Ben Pfaff <blp@cs.stanford.edu> - 2011-09-14 19:58 -0700
Re: Teaching C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-14 21:55 -0600
Re: Teaching C James Kuyper <jameskuyper@verizon.net> - 2011-09-15 06:54 -0400
Re: Teaching C Keith Thompson <kst-u@mib.org> - 2011-09-15 11:58 -0700
Re: Teaching C Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 12:57 -0800
Re: Teaching C Nobody <nobody@nowhere.com> - 2011-09-15 14:25 +0100
Re: Teaching C Seebs <usenet-nospam@seebs.net> - 2011-09-16 22:00 +0000
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-14 12:54 -0400
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-14 13:26 -0400
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 19:33 +0200
Re: Teaching C (was Re: hexump.c) jameskuyper <jameskuyper@verizon.net> - 2011-09-14 11:33 -0700
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 21:17 +0200
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-16 11:47 -0400
Re: Teaching C (was Re: hexump.c) Seebs <usenet-nospam@seebs.net> - 2011-09-14 20:43 +0000
Re: Teaching C (was Re: hexump.c) Nobody <nobody@nowhere.com> - 2011-09-14 22:35 +0100
Re: Teaching C (was Re: hexump.c) gordonb.8a7i1@burditt.org (Gordon Burditt) - 2011-09-14 17:31 -0500
Re: Teaching C (was Re: hexump.c) jacob navia <jacob@spamsink.net> - 2011-09-14 19:32 +0200
Re: Teaching C (was Re: hexump.c) Kenneth Brody <kenbrody@spamcop.net> - 2011-09-16 11:27 -0400
Re: Teaching C (was Re: hexump.c) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-16 08:49 -0700
Re: Teaching C (was Re: hexump.c) James Kuyper <jameskuyper@verizon.net> - 2011-09-17 15:04 -0400
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-13 20:31 -0700
Re: hexump.c Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-14 03:22 -0700
Re: hexump.c "BartC" <bc@freeuk.com> - 2011-09-14 11:40 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 13:54 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-14 13:50 +0100
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 11:35 -0700
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-14 19:12 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-14 15:31 -0700
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-15 00:59 +0200
Re: hexump.c Kleuskes & Moos <kleuske@somewhere.else.net> - 2011-09-14 23:14 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-15 08:52 -0700
Re: hexump.c Jens Gustedt <jens.gustedt@loria.fr> - 2011-09-14 21:22 +0200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 21:26 +0200
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-15 07:32 +1200
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-14 21:44 +0200
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 13:49 -0700
Re: hexump.c Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-09-16 00:50 +0300
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-15 18:34 -0700
Re: hexump.c Keith Thompson <kst-u@mib.org> - 2011-09-14 12:16 -0700
Hypocrites jacob navia <jacob@spamsink.net> - 2011-09-14 21:40 +0200
Re: Hypocrites Keith Thompson <kst-u@mib.org> - 2011-09-14 19:11 -0700
Re: hexump.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-14 15:05 +0100
Re: hexump.c Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-14 07:56 -0700
Re: hexump.c "BartC" <bc@freeuk.com> - 2011-09-14 17:23 +0100
Re: hexump.c Seebs <usenet-nospam@seebs.net> - 2011-09-14 19:12 +0000
Re: hexump.c John Bode <jfbode1029@gmail.com> - 2011-09-14 15:24 -0700
Re: hexump.c gordonb.ik17p@burditt.org (Gordon Burditt) - 2011-09-09 18:16 -0500
Re: hexump.c Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-12 22:24 +0000
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-09 20:33 -0400
Re: hexump.c Ian Collins <ian-news@hotmail.com> - 2011-09-10 12:42 +1200
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-10 17:16 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 10:03 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-10 10:04 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 11:41 +0200
Re: hexump.c pete <pfiland@mindspring.com> - 2011-09-10 05:51 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 12:38 +0200
Re: hexump.c Nobody <nobody@nowhere.com> - 2011-09-10 17:53 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 12:46 +0200
Re: hexump.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-09-10 13:03 +0100
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-10 15:34 +0200
Re: hexump.c "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-09-10 17:37 -0400
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-11 00:10 +0200
Re: hexump.c Patrick Scheible <kkt@zipcon.net> - 2011-09-10 21:03 -0700
Re: hexump.c Barry Schwarz <schwarz45@yahoo.com> - 2011-09-11 00:37 -0700
Re: hexump.c jacob navia <jacob@spamsink.net> - 2011-09-11 13:56 +0200
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