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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: fseek under IBM MVS |
| Date | 2014-12-17 14:33 -0800 |
| Organization | None to speak of |
| Message-ID | <lnioh9ewj3.fsf@nuthaus.mib.org> (permalink) |
| References | <m6kumm$sfe$1@speranza.aioe.org> <36760209-5dbc-417b-85bb-17993bbe5900@googlegroups.com> <549153d8.2327046@news.xs4all.nl> <lnvbladx5k.fsf@nuthaus.mib.org> <m6sub5$8e4$1@speranza.aioe.org> |
glen herrmannsfeldt <gah@ugcs.caltech.edu> writes:
> Keith Thompson <kst-u@mib.org> wrote:
>> raltbos@xs4all.nl (Richard Bos) writes:
>
> (snip)
>
>>> Apart from the reliability issue, the fseek()/ftell() trick simply is
>>> inefficient, in a way that fstat()/filelength()/GetFileSize()/&c.
>>> aren't, if they're at all well implemented.
>
>> On a system where it works, I woudnl't expect the fseek()/ftell() trick
>> to be particularly inefficient.
>
> By works, you mean for a stream of bytes file system?
I suppose so. More precisly, I'm referring to systems where the
fseek()/ftell() trick will reliably indicate (for a file no longer than
LONG_MAX bytes and assuming the file hasn't changed while this is being
done) the same size as reading the entire file a character at a type and
counting the characters read. Of course I'd expect the latter approach
to be slower.
> For MVS, if you want the exact byte length, for variable length
> records, you have to read the whole file and count them. For FBS,
> you can read just the last track and count it.
I presume that's accurate, but it's not relevant to my point, which
applies only to systems where the fseek()/ftell() trick works reliably.
[...]
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-14 22:16 +0100
Re: fseek under IBM MVS glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-15 01:12 +0000
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-15 09:13 +0100
Re: fseek under IBM MVS glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-15 09:22 +0000
Re: fseek under IBM MVS Kaz Kylheku <kaz@kylheku.com> - 2014-12-15 16:26 +0000
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 09:58 +0000
Re: fseek under IBM MVS BartC <bc@freeuk.com> - 2014-12-17 11:29 +0000
Re: fseek under IBM MVS John Bode <jfbode1029@gmail.com> - 2014-12-15 10:35 -0800
Re: fseek under IBM MVS glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-15 21:33 +0000
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-15 23:45 +0100
Re: fseek under IBM MVS Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2014-12-15 17:56 -0500
Re: fseek under IBM MVS Kaz Kylheku <kaz@kylheku.com> - 2014-12-15 23:05 +0000
Re: fseek under IBM MVS BartC <bc@freeuk.com> - 2014-12-15 23:19 +0000
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-15 16:36 -0800
Re: fseek under IBM MVS Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2014-12-15 20:42 -0500
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-16 01:00 +0100
Re: fseek under IBM MVS glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-16 01:09 +0000
Re: (OT) fseek under IBM MVS Vincenzo Mercuri <nomail@yahoo.it> - 2014-12-16 09:11 +0100
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 10:06 +0000
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-17 11:33 +0100
Re: fseek under IBM MVS John Bode <jfbode1029@gmail.com> - 2014-12-17 08:48 -0800
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 17:26 +0000
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-17 19:46 +0100
Re: fseek under IBM MVS Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 19:28 +0000
Re: fseek under IBM MVS jacob navia <jacob@spamsink.net> - 2014-12-17 21:38 +0100
Re: fseek under IBM MVS Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 21:05 +0000
Re: fseek under IBM MVS Ian Collins <ian-news@hotmail.com> - 2014-12-18 11:37 +1300
Re: fseek under IBM MVS John Bode <jfbode1029@gmail.com> - 2014-12-17 12:43 -0800
Re: fseek under IBM MVS fir <profesor.fir@gmail.com> - 2014-12-19 08:35 -0800
Re: fseek under IBM MVS BartC <bc@freeuk.com> - 2014-12-19 16:51 +0000
Re: fseek under IBM MVS Robert Wessel <robertwessel2@yahoo.com> - 2014-12-19 16:36 -0600
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 10:05 +0000
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-17 09:05 -0800
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 17:29 +0000
Re: fseek under IBM MVS John Bode <jfbode1029@gmail.com> - 2014-12-17 12:55 -0800
Re: fseek under IBM MVS John Bode <jfbode1029@gmail.com> - 2014-12-17 15:02 -0800
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-17 23:37 +0000
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-17 16:11 -0800
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-18 12:06 +0000
Re: fseek under IBM MVS James Kuyper <jameskuyper@verizon.net> - 2014-12-18 11:44 -0500
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-18 11:03 -0800
Re: fseek under IBM MVS raltbos@xs4all.nl (Richard Bos) - 2014-12-19 11:31 +0000
Re: fseek under IBM MVS James Kuyper <jameskuyper@verizon.net> - 2014-12-19 08:03 -0500
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-19 08:08 -0800
Re: fseek under IBM MVS James Kuyper <jameskuyper@verizon.net> - 2014-12-19 11:30 -0500
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-17 15:56 -0800
Re: fseek under IBM MVS Ian Collins <ian-news@hotmail.com> - 2014-12-21 21:37 +1300
Re: fseek under IBM MVS glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-17 21:59 +0000
Re: fseek under IBM MVS Keith Thompson <kst-u@mib.org> - 2014-12-17 14:33 -0800
Re: fseek under IBM MVS "Charles Richmond" <numerist@aquaporin4.com> - 2014-12-18 16:06 -0600
Re: fseek under IBM MVS Siri Crews <chine.bleu@yahoo.com> - 2014-12-17 04:20 -0800
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