Re: Whaddaya think?

From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: Whaddaya think?
Date	2024-06-15 21:17 -0700
Organization	None to speak of
Message-ID	<877cep4j2i.fsf@nosuchdomain.example.com> (permalink)
References	<666ded36$0$958$882e4bbb@reader.netnews.com> <20240616015649.000051a0@yahoo.com> <v4lm16$3s87h$4@dont-email.me> <v4lmso$3sl7n$1@dont-email.me>

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Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> On 16.06.2024 05:26, Lawrence D'Oliveiro wrote:
>> On Sun, 16 Jun 2024 01:56:49 +0300, Michael S wrote:
>> 
>>> If you want to preserve you sanity, never use fscanf().
>> 
>> Quoth the man page <https://manpages.debian.org/3/scanf.3.en.html>:
>> 
>>     It is very difficult to use these functions correctly, and it is
>>     preferable to read entire lines with fgets(3) or getline(3) and
>>     parse them later with sscanf(3) or more specialized functions such
>>     as strtol(3).
>
> This would be also my first impulse, but you'd have to know
> _in advance_ how long the data stream would be; the function
> requires an existing buffer. So you'd anyway need a stepwise
> input. On the plus side there's maybe a better performance
> to read large buffer junks and compose them on demand? But
> a problem is the potential cut of the string of a number; it
> requires additional clumsy handling. So it might anyway be
> better (i.e. much more convenient) to use fscanf() ?

I advise never using any of the *scanf() functions for numeric input
unless you have control over what appears on the input stream.
They have undefined behavior if the input value is out of range.
(I consider this a bug in the language.)  Typical behavior is to
store some arbitrary integer value with no error indication.

As for reading lines, getline() can allocate a buffer long enough
to hold the line, but it's defined by POSIX, not by ISO C.

For the original problem, where the input consists of digits and
whitespace, you could read a character at a time and accumulate the
value of each number.  (You probably want to handle leading signs as
well, which isn't difficult.)  That is admittedly reinventing the
wheel, but the existing wheels aren't entirely round.  You still
have to dynamically allocate the array of ints, assuming you need
to store all of them rather than processing each value as it's read.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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Whaddaya think? DFS <nospam@dfs.com> - 2024-06-15 15:36 -0400
  Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-15 22:33 +0100
  Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-15 23:03 +0100
    Re: Whaddaya think? bart <bc@freeuk.com> - 2024-06-16 00:22 +0100
      Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-16 10:30 +0100
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:52 -0400
      Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-17 00:17 +0100
        Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 08:49 -0400
  Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 15:22 -0700
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 12:20 -0400
      Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 13:54 -0700
      Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-16 22:41 -0400
        Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-16 22:45 -0700
        Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-17 07:39 +0000
          Re: Whaddaya think? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-17 01:22 -0700
          Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:50 -0400
            Re: Whaddaya think? Richard Harnden <richard.nospam@gmail.invalid> - 2024-06-17 16:23 +0100
              Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-17 18:46 +0200
              Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-22 22:14 +0000
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-22 17:10 -0700
                Re: Whaddaya think? Phil Carmody <pc+usenet@asdf.org> - 2024-06-23 11:20 +0300
          Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 00:19 -0700
            Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 03:10 -0700
              Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 17:24 -0700
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 17:55 -0700
                Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-19 01:58 +0000
        Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 08:50 -0400
          Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-17 15:41 +0100
            Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 08:12 +0200
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 03:07 -0700
      Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 00:30 -0400
  Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 01:56 +0300
    Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-16 03:26 +0000
      Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 05:41 +0200
        Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 21:17 -0700
          Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-16 04:41 +0000
          Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 06:44 +0200
            Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:09 -0400
              Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-16 17:56 +0200
                Re: Whaddaya think? bart <bc@freeuk.com> - 2024-06-16 18:14 +0100
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-17 14:44 +0200
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:52 -0400
        Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 06:51 +0200
          Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 22:21 -0700
            Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 07:41 +0200
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 22:49 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:29 +0200
                Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 16:04 +0100
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 17:13 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 13:32 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:41 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 23:20 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:16 +0200
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 09:38 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 16:17 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 07:09 +0200
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-18 03:25 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 02:57 -0700
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 16:15 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 08:02 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 19:07 -0700
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-19 09:50 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-19 13:13 -0700
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 02:21 -0400
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:22 +0200
              Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 11:11 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:07 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 12:38 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 12:03 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 14:31 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 17:37 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-17 00:45 +0300
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 17:06 -0700
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-16 22:40 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:52 +0200
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:45 -0400
                Re: Whaddaya think? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-17 13:16 -0700
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 17:07 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 15:48 -0700
                Re: Whaddaya think? scott@slp53.sl.home (Scott Lurndal) - 2024-06-17 22:48 +0000
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 15:44 -0700
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-18 15:00 +0200
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 06:57 +0200
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 00:25 -0700
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 02:38 -0400
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 17:01 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:48 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 23:29 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:35 +0200
        Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 08:19 +0100
        Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 10:44 +0300
          Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:13 +0200
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:03 -0400
  Re: Whaddaya think? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-16 15:52 +0000
    Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 17:17 +0100
    Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-18 08:06 +0000

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