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| From | Rainer Weikusat <rweikusat@talktalk.net> |
|---|---|
| Newsgroups | comp.unix.shell, comp.unix.programmer, comp.lang.misc |
| Subject | Re: Command Languages Versus Programming Languages |
| Date | 2024-11-22 15:41 +0000 |
| Message-ID | <877c8vtgx6.fsf@doppelsaurus.mobileactivedefense.com> (permalink) |
| References | <uu54la$3su5b$6@dont-email.me> <875xohbxre.fsf@doppelsaurus.mobileactivedefense.com> <vhngoi$2p6$1@reader2.panix.com> <874j40sk01.fsf@doppelsaurus.mobileactivedefense.com> <vhq11q$nq7$1@reader2.panix.com> |
Cross-posted to 3 groups.
cross@spitfire.i.gajendra.net (Dan Cross) writes:
> Rainer Weikusat <rweikusat@talktalk.net> wrote:
>>cross@spitfire.i.gajendra.net (Dan Cross) writes:
>>> Rainer Weikusat <rweikusat@talktalk.net> wrote:
>>>>Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>>>>
>>>>[...]
>>>>
>>>>> Personally I think that writing bulky procedural stuff for something
>>>>> like [0-9]+ can only be much worse, and that further abbreviations
>>>>> like \d+ are the better direction to go if targeting a good interface.
>>>>> YMMV.
>>>>
>>>>Assuming that p is a pointer to the current position in a string, e is a
>>>>pointer to the end of it (ie, point just past the last byte) and -
>>>>that's important - both are pointers to unsigned quantities, the 'bulky'
>>>>C equivalent of [0-9]+ is
>>>>
>>>>while (p < e && *p - '0' < 10) ++p;
>>>>
>>>>That's not too bad. And it's really a hell lot faster than a
>>>>general-purpose automaton programmed to recognize the same pattern
>>>>(which might not matter most of the time, but sometimes, it does).
>>>
>>> It's also not exactly right. `[0-9]+` would match one or more
>>> characters; this possibly matches 0 (ie, if `p` pointed to
>>> something that wasn't a digit).
>>
>>The regex won't match any digits if there aren't any. In this case, the
>>match will fail. I didn't include the code for handling that because it
>>seemed pretty pointless for the example.
>
> That's rather the point though, isn't it? The program snippet
> (modulo the promotion to signed int via the "usual arithmetic
> conversions" before the subtraction and comparison giving you
> unexpected values; nothing to do with whether `char` is signed
> or not) is a snippet that advances a pointer while it points to
> a digit, starting at the current pointer position; that is, it
> just increments a pointer over a run of digits.
That's the core part of matching someting equivalent to the regex [0-9]+
and the only part of it is which is at least remotely interesting.
> But that's not the same as a regex matcher, which has a semantic
> notion of success or failure. I could run your snippet against
> a string such as, say, "ZZZZZZ" and it would "succeed" just as
> it would against an empty string or a string of one or more
> digits.
Why do you believe that p being equivalent to the starting position
would be considered a "successful match", considering that this
obviously doesn't make any sense?
[...]
> By the way, something that _would_ match `^[0-9]+$` might be:
[too much code]
Something which would match [0-9]+ in its first argument (if any) would
be:
#include "string.h"
#include "stdlib.h"
int main(int argc, char **argv)
{
char *p;
unsigned c;
p = argv[1];
if (!p) exit(1);
while (c = *p, c && c - '0' > 10) ++p;
if (!c) exit(1);
return 0;
}
but that's 14 lines of text, 13 of which have absolutely no relation to
the problem of recognizing a digit.
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Re: Command Languages Versus Programming Languages Bozo User <anthk@disroot.org> - 2024-09-30 20:04 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-09-30 21:04 +0000
Re: Command Languages Versus Programming Languages usuario <anthk@disroot.org> - 2024-10-01 20:18 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-02 07:10 +0000
Re: Command Languages Versus Programming Languages usuario <anthk@disroot.org> - 2024-10-02 12:52 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-02 16:00 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-09 22:25 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-10 08:38 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-10 16:09 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-10 15:34 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-10 17:55 +0100
Re: Command Languages Versus Programming Languages Kaz Kylheku <643-408-1753@kylheku.com> - 2024-10-10 19:14 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-10 21:31 +0100
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-11 00:09 +0100
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-11 15:47 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-11 15:15 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-11 15:45 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-11 15:59 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-11 16:28 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-12 08:39 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-12 13:53 +0000
Re: Command Languages Versus Programming Languages Muttley@dastardlyhq.com - 2024-10-12 14:50 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-10-12 15:32 +0000
Re: Command Languages Versus Programming Languages Muttley@dastardlyhq.com - 2024-10-12 15:51 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-12 16:36 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 08:18 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 13:43 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 14:54 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 15:30 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 16:02 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 20:15 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-14 08:25 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-14 13:38 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-14 14:47 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-10-14 14:53 +0000
Re: Command Languages Versus Programming Languages David Brown <david.brown@hesbynett.no> - 2024-10-14 17:27 +0200
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-13 21:09 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-13 21:08 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-10-13 15:08 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 15:52 +0000
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-13 17:20 +0100
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 20:29 +0000
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-14 01:20 +0100
Re: On overly rigid definitions (was Re: Command Languages Versus Programming Languages) cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-14 00:58 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-10-13 15:02 +0000
Re: Command Languages Versus Programming Languages Kaz Kylheku <643-408-1753@kylheku.com> - 2024-10-13 16:31 +0000
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-13 20:06 +0100
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-10-13 20:30 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-10-11 16:37 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-11 19:01 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-12 08:40 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-11 20:58 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-12 08:42 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-12 14:37 +0100
Re: Command Languages Versus Programming Languages Christian Weisgerber <naddy@mips.inka.de> - 2024-10-12 17:49 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 08:20 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-13 21:25 +0100
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-12 20:50 +0100
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-12 21:25 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 08:22 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-13 20:33 +0000
Re: Command Languages Versus Programming Languages Bart <bc@freeuk.com> - 2024-10-11 00:07 +0100
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-11 16:15 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-11 08:17 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-11 19:37 +0100
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-11 01:33 +0000
Re: Command Languages Versus Programming Languages Eric Pozharski <apple.universe@posteo.net> - 2024-10-12 16:39 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-13 08:19 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-13 14:55 +0200
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-13 21:33 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-14 08:28 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-14 11:38 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-14 11:05 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-10-14 16:04 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-10-14 15:39 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-13 20:34 +0000
Re: Command Languages Versus Programming Languages Sebastian <sebastian@here.com.invalid> - 2024-11-11 07:31 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-11 10:06 +0000
Re: Command Languages Versus Programming Languages Wolfgang Agnes <wagnes@jemoni.to> - 2024-11-11 08:28 -0300
Re: Command Languages Versus Programming Languages Muttley@dastardlyhq.com - 2024-11-11 16:21 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-11 20:55 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-12 10:14 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-12 09:21 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-12 10:31 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-12 09:53 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-12 15:05 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-12 15:09 +0000
Re: Command Languages Versus Programming Languages Wolfgang Agnes <wagnes@jemoni.to> - 2024-11-12 13:47 -0300
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-11 21:24 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-12 10:23 +0100
Re: Command Languages Versus Programming Languages Wolfgang Agnes <wagnes@jemoni.to> - 2024-11-12 13:50 -0300
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-12 20:29 +0000
Re: Command Languages Versus Programming Languages merlyn@stonehenge.com (Randal L. Schwartz) - 2024-11-19 18:43 -0800
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-20 04:34 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-20 08:21 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-20 11:51 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-20 11:30 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-20 16:38 +0100
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-20 16:38 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-20 17:54 +0000
Re: Command Languages Versus Programming Languages John Ames <commodorejohn@gmail.com> - 2024-11-20 10:03 -0800
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-21 08:18 +0000
Re: Command Languages Versus Programming Languages John Ames <commodorejohn@gmail.com> - 2024-11-21 07:56 -0800
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-21 14:13 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-21 16:06 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-21 08:13 +0000
Re: Command Languages Versus Programming Languages John Ames <commodorejohn@gmail.com> - 2024-11-21 07:58 -0800
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-20 17:50 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-21 14:40 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-21 15:07 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 13:30 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 15:41 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 15:52 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 17:18 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 17:35 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 17:43 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 17:43 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 17:17 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 17:48 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 18:12 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 18:48 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 19:05 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 19:24 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 19:46 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-11-22 18:14 +0000
Re: Command Languages Versus Programming Languages scott@slp53.sl.home (Scott Lurndal) - 2024-11-22 18:22 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 18:30 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 18:59 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 19:15 +0000
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 19:26 +0000
Re: Command Languages Versus Programming Languages cross@spitfire.i.gajendra.net (Dan Cross) - 2024-11-22 19:51 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-22 12:14 +0100
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-22 11:56 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-22 20:33 +0100
Re: Command Languages Versus Programming Languages Kaz Kylheku <643-408-1753@kylheku.com> - 2024-11-21 19:12 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-22 10:09 +0000
Re: Command Languages Versus Programming Languages Kaz Kylheku <643-408-1753@kylheku.com> - 2024-11-22 18:18 +0000
Re: Command Languages Versus Programming Languages Muttley@dastardlyhq.com - 2024-11-23 11:40 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-22 12:17 +0100
Re: Command Languages Versus Programming Languages Kaz Kylheku <643-408-1753@kylheku.com> - 2024-11-22 18:19 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-22 20:20 +0100
Re: Command Languages Versus Programming Languages Ed Morton <mortonspam@gmail.com> - 2024-11-20 05:46 -0600
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-20 12:27 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-20 21:43 +0000
Re: Command Languages Versus Programming Languages Muttley@DastartdlyHQ.org - 2024-11-21 08:15 +0000
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-21 22:05 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-22 12:47 +0100
Re: Command Languages Versus Programming Languages Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-22 20:41 +0000
Re: Command Languages Versus Programming Languages Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-11-20 16:53 +0100
Re: Command Languages Versus Programming Languages Ed Morton <mortonspam@gmail.com> - 2024-11-23 18:17 -0600
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-20 12:21 +0000
Re: Command Languages Versus Programming Languages merlyn@stonehenge.com (Randal L. Schwartz) - 2024-11-21 05:38 -0800
Re: Command Languages Versus Programming Languages Rainer Weikusat <rweikusat@talktalk.net> - 2024-11-21 17:01 +0000
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