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Groups > comp.lang.c > #164072
| From | Manfred <noname@add.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Can this program be improved? |
| Date | 2021-12-25 23:50 +0100 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <sq877f$dof$1@gioia.aioe.org> (permalink) |
| References | <sq63mi$gom$1@dont-email.me> <sq6b3t$ce5$1@dont-email.me> |
On 12/25/2021 6:44 AM, Andrey Tarasevich wrote:
> 6. Stop piling up all variable declarations at the beginning of the
> function. Declare variables as locally as possible.
Put this way, this is questionable advice, IMO.
Experienced programmers may have your same opinion, but some others,
equally experienced, may label that same programming style as sloppy -
I've seen some myself.
In order to turn this opinion into good advice, I think there is more to
add to it:
1) Functions should perform simple, well defined tasks, which implies
that complex tasks should be split into multiple functions. After you do
this, then it becomes natural that you don't have "piles" of local
variables, and you may well have the variables you need at the beginning
of the function and still be "local".
2) Make good use of language constructs to keep counters, indexes etc.
local: for example, instead of declaring a generic counter "n" at the
beginning of the function and reuse it multiple times, prefer the following:
for (int n = 0; n < COUNT; ++n)
{
/* ... */
}
and thus have multiple "for" (and friends) constructs each with its own
counter.
3) If in the function body you have a code section that performs some
specific operation that needs its local variables, you may use a local
scope for it, and declare its variables inside it (check point 1 above
as well):
int myfunction(void)
{
/* ... */
{
int myvar = 42;
/* ... */
}
/* ... */
}
Obviously, the body of language constructs like "if", "for", "while",
"do" make natural local scopes that are good candidates for this purpose.
4) For algorithmic parameters that may affect the entire task, (e.g.
number of months in a year), you may well have a "const" variable at the
beginning of the function. "static const" at the beginning of the source
file is also an option, as well as many others.
>
> 7. Stop using dummy initializers for your variables. It is better to
> leave them uninitialized than initialize them to dummy zeros. This point
> is actually connected to the previous one: once you start declaring
> variables as locally as possible, you'll normally have a meaningful
> initializers for them at the point of declaration.
This is tricky. One of the worst bugs I have ever encountered was
"strlen" being called on an uninitialized string buffer.
I believe the best option is to initialize variables with meaningful
values, which leads to locality, as you say, but with my notes above.
However, as a last resort, it is probably better to leave them
uninitialized, rather than dummy zeros, *if* you have a decent compiler
that will spot its use before assignment.
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Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-25 01:00 +0000
Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-24 21:44 -0800
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2021-12-25 12:56 +0100
Re: Can this program be improved? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-12-25 11:13 -0800
Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-25 23:50 +0100
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 18:52 +0000
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-26 19:22 +0000
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 21:30 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-26 22:02 +0000
Re: Can this program be improved? Richard Damon <Richard@Damon-Family.org> - 2021-12-26 18:24 -0500
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-27 00:47 +0000
Re: Can this program be improved? Guillaume <message@bottle.org> - 2021-12-29 17:52 +0100
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-29 17:49 +0000
Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-29 11:33 -0800
Re: Can this program be improved? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-29 22:45 -0500
Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-30 00:35 -0800
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2021-12-30 10:19 +0100
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 18:19 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 19:33 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 14:37 -0800
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-29 23:09 +0000
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2021-12-29 23:54 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 16:11 -0800
Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:34 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-30 12:49 +0000
Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 21:04 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 02:13 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 16:09 -0800
Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:59 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-29 17:48 -0800
Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 20:47 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-30 01:06 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-30 04:48 -0800
Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-30 18:16 +0100
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 02:20 +0000
Re: Can this program be improved? Manfred <noname@add.invalid> - 2021-12-31 18:25 +0100
Re: Can this program be improved? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-12-31 18:13 -0500
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-31 23:59 +0000
Re: Can this program be improved? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-12-31 16:20 -0800
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-31 16:35 -0800
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 00:53 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-31 20:22 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-31 22:04 -0800
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-01 14:59 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-02 17:22 -0800
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-02 20:49 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 03:09 -0800
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-03 16:22 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-03 14:42 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 14:52 -0800
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 22:58 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 04:27 -0800
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 13:39 +0000
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 00:18 +0100
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-03 15:24 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 15:43 -0800
Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2022-01-03 21:19 -0800
Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-04 09:23 +0100
Re: Can this program be improved? Guillaume <message@bottle.org> - 2022-01-04 18:18 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 10:35 -0800
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-04 14:07 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 15:11 -0800
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-01-04 15:47 -0800
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 18:30 -0800
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 23:46 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-04 18:41 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 10:52 -0800
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 19:00 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 11:15 -0800
Re: Can this program be improved? Guillaume <message@bottle.org> - 2022-01-04 21:57 +0100
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-04 21:02 +0000
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-04 21:38 +0000
Re: Can this program be improved? Manfred <noname@add.invalid> - 2022-01-04 23:01 +0100
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 09:31 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 01:30 -0800
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 14:55 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-04 06:21 -0800
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-04 16:49 +0100
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 15:56 +0000
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-04 15:03 +0000
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 22:54 +0000
Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 09:22 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 03:30 -0800
Re: Can this program be improved? David Brown <david.brown@hesbynett.no> - 2022-01-03 17:22 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 08:48 -0800
Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 18:42 +0100
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-03 17:59 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 11:09 -0800
Re: Can this program be improved? Mateusz Viste <mateusz@xyz.invalid> - 2022-01-03 20:32 +0100
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-03 11:58 -0800
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2022-01-03 18:13 +0000
Re: Can this program be improved? gazelle@shell.xmission.com (Kenny McCormack) - 2022-01-03 20:05 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2022-01-01 16:53 +0000
Re: Can this program be improved? Kaz Kylheku <480-992-1380@kylheku.com> - 2021-12-30 00:29 +0000
Re: Can this program be improved? Bart <bc@freeuk.com> - 2021-12-25 12:47 +0000
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 18:56 +0000
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 17:38 +0000
Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2021-12-25 10:58 -0800
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 19:16 +0000
Re: Can this program be improved? Öö Tiib <ootiib@hot.ee> - 2021-12-25 11:25 -0800
Re: Can this program be improved? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-12-25 15:01 -0800
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-25 23:09 +0000
Re: Can this program be improved? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-12-25 20:56 -0800
Re: Can this program be improved? scott@slp53.sl.home (Scott Lurndal) - 2021-12-25 19:30 +0000
Re: Can this program be improved? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-25 15:50 -0800
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:02 +0000
Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-25 11:53 -0800
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:00 +0000
Re: Can this program be improved? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-12-25 11:22 -0800
Re: Can this program be improved? Manu Raju <MR@invalid.invalid> - 2021-12-26 19:01 +0000
Re: Can this program be improved? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-25 13:27 -0800
Re: Can this program be improved? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-12-25 16:06 -0800
Re: Can this program be improved? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2021-12-29 15:21 +0000
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