Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #386011
| From | Michael S <already5chosen@yahoo.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Whaddaya think? |
| Date | 2024-06-16 11:11 +0300 |
| Organization | A noiseless patient Spider |
| Message-ID | <20240616111134.00001f18@yahoo.com> (permalink) |
| References | (2 earlier) <v4lm16$3s87h$4@dont-email.me> <v4lmso$3sl7n$1@dont-email.me> <v4lr0m$3tbpj$1@dont-email.me> <8734pd4g3s.fsf@nosuchdomain.example.com> <v4ltuj$3trj2$1@dont-email.me> |
On Sun, 16 Jun 2024 07:41:38 +0200
Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> On 16.06.2024 07:21, Keith Thompson wrote:
> > Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> >> On 16.06.2024 05:41, Janis Papanagnou wrote:
> >>> 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. [...]
> >>
> >> Would it be sensible to have a malloc()'ed buffer used for the
> >> first fgets() and then subsequent fgets() work on the realloc()'ed
> >> part? I suppose the previously set data in the malloc area would
> >> be retained so that there's no re-composition of cut numbers
> >> necessary?
> >
> > Sure. "The contents of the new object shall be the same as that of
> > the old object prior to deallocation, up to the lesser of the new
> > and old sizes."
> >
> > Keep in mind that you can't call realloc() on a non-null pointer
> > that wasn't allocated by an allocation function.
>
> Thanks. - I've just tried it with this ad hoc test code
>
> #include <stdlib.h>
> #include <stdio.h>
>
> void main (int argc, char * argv[])
> {
> int chunk = 10;
> int bufsize = chunk+1;
> char * buf = malloc(bufsize);
> char * anchor = buf;
> while (fgets(buf, chunk+1, stdin) != NULL)
> if (realloc(anchor, bufsize += chunk) != NULL)
> buf += chunk;
> puts(anchor);
> }
>
Not sure what this code is supposed to do.
However it looks unlikely that it does what you meant for it to do.
I recommend to read the [f*****g] manual.
https://cplusplus.com/reference/cstdio/fgets/
https://cplusplus.com/reference/cstdlib/realloc/
> I wonder whether it can be simplified by making malloc() obsolete
> and using realloc() in a redesigned loop.
>
> Janis
>
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar
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
csiph-web