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Groups > comp.lang.c > #67230 > unrolled thread

How to read a data file whose size is unknown in C?

Started byfl <rxjwg98@gmail.com>
First post2015-08-12 15:28 -0700
Last post2015-08-14 09:03 -0700
Articles 20 on this page of 164 — 27 participants

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  How to read a data file whose size is unknown in C? fl <rxjwg98@gmail.com> - 2015-08-12 15:28 -0700
    Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-12 23:52 +0100
      Re: How to read a data file whose size is unknown in C? fl <rxjwg98@gmail.com> - 2015-08-12 16:13 -0700
        Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-13 00:33 +0100
        Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-13 00:06 +0000
          Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-13 20:50 +0000
            Re: How to read a data file whose size is unknown in C? Stephen Sprunk <stephen@sprunk.org> - 2015-08-17 13:38 -0500
              Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-17 14:48 -0400
              Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-18 11:10 +0100
                Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-18 15:01 +0100
        Re: How to read a data file whose size is unknown in C? gordonb.8n5lc@burditt.org (Gordon Burditt) - 2015-08-14 02:33 -0500
          Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-14 10:06 +0200
            Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-14 09:14 +0100
              Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-14 21:27 +0000
                Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 09:52 +0200
            Re: How to read a data file whose size is unknown in C? Nobody <nobody@nowhere.invalid> - 2015-08-15 01:17 +0100
              Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 10:27 +0200
                Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-15 18:09 +0000
                  Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 22:05 +0200
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 19:17 -0700
                Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 13:50 -0700
                  Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-15 21:37 +0100
                    Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 23:33 +0200
                      Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-15 22:58 +0100
                        Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-16 00:08 +0200
                          Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-16 00:40 +0100
                            Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-16 02:23 +0200
                              Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 19:37 -0700
                            Re: How to read a data file whose size is unknown in C? gazelle@shell.xmission.com (Kenny McCormack) - 2015-08-16 15:35 +0000
                              Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-16 10:31 -0700
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 19:21 -0700
                  Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 23:31 +0200
                  Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-16 03:38 -0700
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-16 17:29 -0700
                      Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-17 01:46 -0700
                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-17 09:03 -0700
                Re: How to read a data file whose size is unknown in C? Nobody <nobody@nowhere.invalid> - 2015-08-16 03:23 +0100
                Re: How to read a data file whose size is unknown in C? Philip Lantz <prl@canterey.us> - 2015-08-17 00:56 -0700
                  Re: How to read a data file whose size is unknown in C? Philip Lantz <prl@canterey.us> - 2015-08-17 01:08 -0700
                  Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-17 10:20 +0200
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-17 09:01 -0700
              Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-15 11:31 +0100
                Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 14:01 -0700
                  Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-15 22:28 +0100
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 19:29 -0700
                      Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-16 10:50 +0100
                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-16 17:40 -0700
                          Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-16 20:22 -0700
                            Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-16 21:27 -0700
                              Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-17 01:31 -0700
                              Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-17 20:25 +0000
                                Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-17 16:29 -0700
                                  Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-17 23:43 +0000
                                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-17 18:20 -0700
                              Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-17 19:10 -0700
                                Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-18 05:26 +0000
                                  Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-22 14:23 +0000
                                Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-18 04:23 -0700
                                  Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-18 17:39 -0700
                                Re: How to read a data file whose size is unknown in C? Ike Naar <ike@iceland.freeshell.org> - 2015-08-18 16:49 +0000
                                  Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-18 17:42 -0700
                                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-18 19:57 -0700
                                      Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-19 16:12 -0700
                                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-19 18:04 -0700
                                          Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-20 16:52 -0700
                                            Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-20 18:18 -0700
                                            Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-21 20:39 +0000
                                              Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-21 17:17 -0700
                                                Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-21 19:35 -0700
                                                  Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-22 18:28 -0700
                                                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-22 22:43 -0700
                                                Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-22 00:07 -0400
                                                  Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-22 18:59 -0700
                                                    Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-22 23:22 -0400
                                                      Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-23 19:17 -0700
                                                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-23 21:35 -0700
                                                          Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-24 16:59 -0700
                                                            Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-24 17:57 -0700
                                                              Re: How to read a data file whose size is unknown in C? Philip Lantz <prl@canterey.us> - 2015-08-25 01:09 -0700
                                                                Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-25 19:03 -0700
                                                                  Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-25 22:16 -0400
                                                                    Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-26 14:29 -0700
                                                                      Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-26 18:28 -0400
                                                                        Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-26 19:25 -0700
                                                                          Re: How to read a data file whose size is unknown in C? David Brown <david.brown@hesbynett.no> - 2015-08-27 10:07 +0200
                                                                          Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-27 09:18 -0700
                                                                            Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-27 18:04 +0000
                                                                              Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-27 11:15 -0700
                                                                                Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-27 21:10 +0000
                                                                              Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-27 15:54 -0700
                                                                              Re: How to read a data file whose size is unknown in C? David Brown <david.brown@hesbynett.no> - 2015-08-28 09:28 +0200
                                                                            Re: How to read a data file whose size is unknown in C? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-08-27 13:12 -0600
                                                                              Re: How to read a data file whose size is unknown in C? David Brown <david.brown@hesbynett.no> - 2015-08-28 09:35 +0200
                                                              Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-25 04:28 -0700
                                                        Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-24 00:19 -0400
                                                        Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-24 00:31 -0700
                                                          Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-24 17:06 -0700
                                                Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-22 14:25 +0000
                                                Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-22 10:45 -0400
                                            Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-21 17:40 -0400
                                    Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-19 00:40 -0400
                                      Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-19 05:38 +0000
                                        Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-19 10:20 -0400
                    Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-22 14:22 +0000
            Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-22 14:21 +0000
          Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-14 08:48 -0400
      Re: How to read a data file whose size is unknown in C? fl <rxjwg98@gmail.com> - 2015-08-12 16:21 -0700
        Re: How to read a data file whose size is unknown in C? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-08-12 19:44 -0600
        Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-12 22:04 -0400
      Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-13 00:44 +0100
        Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-13 01:04 +0100
          Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-13 11:31 +0100
            Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-13 11:51 +0100
            Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-13 08:49 -0700
              Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-13 17:45 +0100
                Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-14 11:11 +0100
                  Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-14 11:34 +0100
                    Re: How to read a data file whose size is unknown in C? Robert Wessel <robertwessel2@yahoo.com> - 2015-08-14 12:21 -0500
                      Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-14 19:07 +0100
                        Re: How to read a data file whose size is unknown in C? Robert Wessel <robertwessel2@yahoo.com> - 2015-08-14 16:08 -0500
                          Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 09:51 +0200
                            Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-15 12:36 -0700
                              Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-15 22:26 +0200
                              Re: How to read a data file whose size is unknown in C? raltbos@xs4all.nl (Richard Bos) - 2015-08-22 14:26 +0000
                                Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-22 08:11 -0700
                            Re: How to read a data file whose size is unknown in C? Robert Wessel <robertwessel2@yahoo.com> - 2015-08-16 00:05 -0500
                              Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-16 09:08 -0400
                                Re: How to read a data file whose size is unknown in C? gazelle@shell.xmission.com (Kenny McCormack) - 2015-08-16 15:22 +0000
                              Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-16 17:28 -0700
                  Re: How to read a data file whose size is unknown in C? Tonton Th <tTh@nowhere.invalid> - 2015-08-14 11:06 +0000
                  Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-14 09:28 -0700
            Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-13 18:56 +0000
              Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-13 13:39 -0700
              Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-14 00:21 +0100
                Re: How to read a data file whose size is unknown in C? Ian Collins <ian-news@hotmail.com> - 2015-08-14 12:26 +1200
                  Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-14 11:00 +0100
                    Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-14 11:30 +0100
                      Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-14 12:31 +0100
                        Re: How to read a data file whose size is unknown in C? "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-14 04:51 -0700
                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-14 09:21 -0700
                    Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-14 09:23 -0700
                      Re: How to read a data file whose size is unknown in C? David Kleinecke <dkleinecke@gmail.com> - 2015-08-14 16:57 -0700
                      Re: How to read a data file whose size is unknown in C? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-08-15 14:49 -0600
                        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-15 19:31 -0700
                Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-14 00:35 +0100
                Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-14 08:57 -0700
                  Re: How to read a data file whose size is unknown in C? Bartc <bc@freeuk.com> - 2015-08-14 17:28 +0100
        Re: How to read a data file whose size is unknown in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-13 00:12 +0000
    Re: How to read a data file whose size is unknown in C? Lőrinczy Zsigmond <nospam@for.me> - 2015-08-13 07:03 +0200
    Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-13 12:38 +0200
      Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-13 13:32 +0100
        Re: How to read a data file whose size is unknown in C? jacobnavia <jacob@jacob.remcomp.fr> - 2015-08-13 14:49 +0200
          Re: How to read a data file whose size is unknown in C? Richard Heathfield <rjh@cpax.org.uk> - 2015-08-13 14:05 +0100
          Re: How to read a data file whose size is unknown in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-13 14:50 +0100
          Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-13 09:14 -0700
          Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-13 12:42 -0400
      Re: How to read a data file whose size is unknown in C? Ken Brody <kenbrody@spamcop.net> - 2015-08-13 10:56 -0400
        Re: How to read a data file whose size is unknown in C? Keith Thompson <kst-u@mib.org> - 2015-08-13 09:16 -0700
          Re: How to read a data file whose size is unknown in C? Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-08-13 18:12 +0200
            Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-13 12:50 -0400
              Re: How to read a data file whose size is unknown in C? Lőrinczy Zsigmond <nospam@for.me> - 2015-08-13 20:07 +0200
                Re: How to read a data file whose size is unknown in C? James Kuyper <jameskuyper@verizon.net> - 2015-08-13 14:38 -0400
    Re: How to read a data file whose size is unknown in C? John Bode <jfbode1029@gmail.com> - 2015-08-13 09:30 -0700
      Re: How to read a data file whose size is unknown in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-14 09:03 -0700

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#67401

FromKeith Thompson <kst-u@mib.org>
Date2015-08-14 09:23 -0700
Message-ID<lny4hdalfk.fsf@kst-u.example.com>
In reply to#67374
Bartc <bc@freeuk.com> writes:
> On 14/08/2015 01:26, Ian Collins wrote:
>> Bartc wrote:
>>> On 13/08/2015 19:56, glen herrmannsfeldt wrote:
>>>>
>>>> To me, input from pipes is the main reason not to use other
>>>> counting methods.
>>>
>>> I don't know anything about pipes. Does fopen() return a handle to a
>>> pipe? If not, then I don't care about them.
>>
>> Yes, if you are using named pipes.
>
> "A named pipe is really just a special kind of file (a FIFO file) on the 
> local hard drive."

Where is that quote from?  I don't believe it's accurate.  A named pipe
lets one process write to it and another read from it, with the data
stored somewhere in the meantime.  It's not necessarily stored on disk.
I actually don't know exactly how named pipes are implemented.

> OK, so we might as well throw out all the random access and file 
> positioning functions, because of the off-chance than a pipe is being 
> read instead of a regular file.
>
> That makes as much sense as avoiding all random indexing into an array 
> in case it might be a linked list or FIFO.

Yes, it makes about as much sense, i.e., not much at all.

-- 
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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#67438

FromDavid Kleinecke <dkleinecke@gmail.com>
Date2015-08-14 16:57 -0700
Message-ID<a27b19e9-9335-4619-919f-a96d7e0dba26@googlegroups.com>
In reply to#67401
On Friday, August 14, 2015 at 9:17:27 AM UTC-7, Keith Thompson wrote:
> Bartc <bc@freeuk.com> writes:
> >
> > "A named pipe is really just a special kind of file (a FIFO file) on the 
> > local hard drive."
> 
> Where is that quote from?  I don't believe it's accurate.  A named pipe
> lets one process write to it and another read from it, with the data
> stored somewhere in the meantime.  It's not necessarily stored on disk.
> I actually don't know exactly how named pipes are implemented.
 
A pipe can be a circular buffer or it can be a nonce file. I think
whoever wrote that quote was thinking of a nonce buffer that is being
written at one end and read at the other. If you really have two 
programs running at the same time (a common experience) an explicitly
circular buffer works well. I think if I were implementing general pipes
I would create a rather large circular buffer - say 4096 bytes - and 
reallocate if it ever clogged.  

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#67468

FromJoe Pfeiffer <pfeiffer@cs.nmsu.edu>
Date2015-08-15 14:49 -0600
Message-ID<1b37zk6zvg.fsf@pfeifferfamily.net>
In reply to#67401
Keith Thompson <kst-u@mib.org> writes:

> Bartc <bc@freeuk.com> writes:
>> On 14/08/2015 01:26, Ian Collins wrote:
>>> Bartc wrote:
>>>> On 13/08/2015 19:56, glen herrmannsfeldt wrote:
>>>>>
>>>>> To me, input from pipes is the main reason not to use other
>>>>> counting methods.
>>>>
>>>> I don't know anything about pipes. Does fopen() return a handle to a
>>>> pipe? If not, then I don't care about them.
>>>
>>> Yes, if you are using named pipes.
>>
>> "A named pipe is really just a special kind of file (a FIFO file) on the 
>> local hard drive."
>
> Where is that quote from?  I don't believe it's accurate.  A named pipe
> lets one process write to it and another read from it, with the data
> stored somewhere in the meantime.  It's not necessarily stored on disk.
> I actually don't know exactly how named pipes are implemented.

It would be better if he'd said it was a kind of special file (special
file being Unix terminology for the object in filesystem space that's
mapped to a device driver).

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#67515

FromKeith Thompson <kst-u@mib.org>
Date2015-08-15 19:31 -0700
Message-ID<lnmvxs7ymy.fsf@kst-u.example.com>
In reply to#67468
Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
> Keith Thompson <kst-u@mib.org> writes:
>> Bartc <bc@freeuk.com> writes:
>>> On 14/08/2015 01:26, Ian Collins wrote:
>>>> Bartc wrote:
>>>>> On 13/08/2015 19:56, glen herrmannsfeldt wrote:
>>>>>>
>>>>>> To me, input from pipes is the main reason not to use other
>>>>>> counting methods.
>>>>>
>>>>> I don't know anything about pipes. Does fopen() return a handle to a
>>>>> pipe? If not, then I don't care about them.
>>>>
>>>> Yes, if you are using named pipes.
>>>
>>> "A named pipe is really just a special kind of file (a FIFO file) on the 
>>> local hard drive."
>>
>> Where is that quote from?  I don't believe it's accurate.  A named pipe
>> lets one process write to it and another read from it, with the data
>> stored somewhere in the meantime.  It's not necessarily stored on disk.
>> I actually don't know exactly how named pipes are implemented.
>
> It would be better if he'd said it was a kind of special file (special
> file being Unix terminology for the object in filesystem space that's
> mapped to a device driver).

The point is that it's not (necessarily) "on the local hard drive".  It
does have a directory entry, which means you can access it as if it were
an ordinary file (except that it's not seekable), but the contents are
not (necessarily) on disk.

-- 
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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#67349

FromRichard Heathfield <rjh@cpax.org.uk>
Date2015-08-14 00:35 +0100
Message-ID<mqj9gp$pmh$1@dont-email.me>
In reply to#67344
On 14/08/15 00:21, Bartc wrote:

<snip>

> (Actually I'm surprised that fseek and ftell haven't been deprecated
> since they are apparently so completely useless according to the
> opinions here!)

By the same reasoning, hammers are useless because you're not supposed 
to use them to drive screws.

The fseek and ftell functions can be invaluable. For example, imagine 
that you are reading a file that you can't store in memory for some 
reason (maybe it's too big), and you need more than one byte of 
lookahead (so ungetc can't help you). You use ftell to note down your 
position in the file, and then you go explore the next few bytes, 
assuming some particular variant of your file's grammar. If you then 
discover that the assumption was wrong, you can use fseek to get back to 
where you were and try the next variant.

The file length trick is just a trick. It isn't what the functions were 
designed for.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within

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#67398

FromKeith Thompson <kst-u@mib.org>
Date2015-08-14 08:57 -0700
Message-ID<ln7foxc177.fsf@kst-u.example.com>
In reply to#67344
Bartc <bc@freeuk.com> writes:
[...]
>> To me, input from pipes is the main reason not to use other
>> counting methods.
>
> I don't know anything about pipes.

Perhaps you should learn.

>                                    Does fopen() return a handle to a 
> pipe?

It can.  Unix-like systems have *named pipes*, which have directory
entries like ordinary files and can be opened by fopen().  The POSIX
popen() function returns a FILE* referring to a pipe.  The pipe()
system call creates a pipe and gives you a pair of file descriptors
(not FILE*s) referring to it.  You can use fdopen() to get a FILE* from
a file descriptor, and fileno() to get a file descriptor from a FILE*.

And it's very common for stdin, stdout, and/or stderr to refer to a
pipe.

From a program's point of view, the main difference between a FILE*
referring to a pipe and a FILE* referring to an ordinary file is that
fseek() and ftell() don't work on pipes (and they cleanly report an
error if you call them).

[...]

> Someone mentioned the OP is trying to read or load an image file. Well 
> I'm looking the details of a jpg file right now: it's 355436 bytes in 
> length, it hasn't been updated since 2006, and is located on my random 
> access hard drive within a Windows file system (probably NTFS).
>
> Any reason why C's fseek and ftell functions shouldn't work on this 
> file? Not just to establish the size, but to be able to do random access 
> or to find out which offset in the file is going to be read on the next 
> fgetc().

No reason that I can think of -- assuming you access it as a file.

But consider this.  I have a jpg image file on my computer called
"albatross.jpg".  The "display" command, part of ImageMagick, displays
an image on my screen.  This command works:

    display albatross.jpg

So does this:

    cat albatross.jpg | display

(Normally that would be "display < albatross.jpg", but I wanted to show
the use of pipes clearly.)

I've mentioned elsewhere that "view /proc/stat" works, even though
/proc/stat is a pseudo-file for which the OS reports a size of 0.

On the other hand, if it's convenient to write a program that only works
if a given stream is seekable that's fine.  Working correctly on pipes
can be convenient for users, but it's not mandatory.

> (Actually I'm surprised that fseek and ftell haven't been deprecated 
> since they are apparently so completely useless according to the 
> opinions here!)

Nobody has been saying that.  We've merely been pointing out that using
fseek and ftell to determine the size of a file is not 100% reliable,
and that if a program is already using system-specific functions, it
might as well use them to determine the size of a file if it needs to.

-- 
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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#67403

FromBartc <bc@freeuk.com>
Date2015-08-14 17:28 +0100
Message-ID<mql4si$j3k$1@dont-email.me>
In reply to#67398
On 14/08/2015 16:57, Keith Thompson wrote:
> Bartc <bc@freeuk.com> writes:

>> Someone mentioned the OP is trying to read or load an image file.

>> Any reason why C's fseek and ftell functions shouldn't work on this
>> file? Not just to establish the size, but to be able to do random access
>> or to find out which offset in the file is going to be read on the next
>> fgetc().
>
> No reason that I can think of -- assuming you access it as a file.
>
> But consider this.  I have a jpg image file on my computer called
> "albatross.jpg".  The "display" command, part of ImageMagick, displays
> an image on my screen.  This command works:
>
>      display albatross.jpg
>
> So does this:
>
>      cat albatross.jpg | display
>
> (Normally that would be "display < albatross.jpg", but I wanted to show
> the use of pipes clearly.)

This doesn't contradict anything I've been saying.

Presumably, if display doesn't see any command-line arguments, then it 
starts looking at stdin. And if that seems like it could be the start of 
a JPG file, then it will try loading binary data from stdin instead of 
being given an explicit filename.

But it is obvious that you wouldn't use seek on stdin or try to obtain 
its size. Although loading critical binary files files from stdin (where 
you might get extra carriage returns or somehow miss the EOF, or can 
risk hanging waiting for user input if something goes wrong) is not 
something I would ever attempt; it's just too crude.

Using proper files though is much better, they will be better behaved 
and you know exactly what to expect. And with complex files, perhaps 
containing multiple resources, if means you might be able to read only 
the section of interest without just blindly processing the entire file.

It's just the difference between dealing with a book, or a never-ending 
ticker-tape. It's possible to deal with both.

-- 
Bartc

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#67244

Fromglen herrmannsfeldt <gah@ugcs.caltech.edu>
Date2015-08-13 00:12 +0000
Message-ID<mqgndp$99j$1@speranza.aioe.org>
In reply to#67241
Bartc <bc@freeuk.com> wrote:
> On 12/08/2015 23:52, Richard Heathfield wrote:
(snip) 
>> No, there is no standard way to find out the size of a file. Someone
>> once cobbled together a bodge using fseek and ftell, which is not only
>> not guaranteed to work but is actually an appalling misuse of those
>> functions.
 
> Suppose you started to read a book but wanted to find out how many pages 
> you had ahead of you; what is wrong with looking at the end of the book 
> and glancing at the page number, then going back to the beginning?

OK, but say you want to know the number of words?  

Not quite as easy.

For a real example, IBM's z/OS keeps track of the number of disk
tracks a file uses, but not how full each track is. Specifically,
it doesn't know how much is (not) in the gaps between blocks.
(And even more, there could be unused tracks after the end.)

There is an OS call to find out the number of tracks, similar
to the number of pages in a book, but not if you want the number
of bytes.  If you multiply by the track size, which you can also
find out, you know that the file is smaller.

In the case of DOS/Windows, a text file has "\r\n" line endings,
but not when read in. If you count the bytes in the file, you will
be a little larger than the actual number of characters to read in.
 
>>  The best way really is to keep reading it until you've read
>> it, growing the storage area as you go.
 
> Except the file itself could grow, shrink or be updated at the same 
> time. Reading a file into memory could actually be impossible!

-- glen

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#67255

FromLőrinczy Zsigmond <nospam@for.me>
Date2015-08-13 07:03 +0200
Message-ID<mqh8ea$a9q$1@speranza.aioe.org>
In reply to#67230
On 2015.08.13. 0:28, fl wrote:
> Hi,
>
> I had a test and I don't know what is the catch:
>
> How to read a data file whose size is unknown in C?

Use read, fread, fgets, fgetc or similar function...

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#67266

Fromjacobnavia <jacob@jacob.remcomp.fr>
Date2015-08-13 12:38 +0200
Message-ID<mqhrun$9o$1@dont-email.me>
In reply to#67230
Le 13/08/2015 00:28, fl a écrit :
> Hi,
>
> I had a test and I don't know what is the catch:
>
> How to read a data file whose size is unknown in C?
>
>
> The data file could be a .img file.
>
> I thought about fseek(), etc., but I was not sure at all and didn't say
> anything about it. Whether is it about some function on the end of the file?
>
>
> Thanks,
>

If you use fseek to go to the end of the file, then ftell to store the 
size, you can get the length of the file on disc.

This solution will work in the following systems:

Android
iOs (Apple)
Linux
Mac OS X
All other POSIX systems
Windows (all versions)
MSDOS

This makes for a very portable solution that can break in some odd 
systems. If your system is in the list above and you do not care about 
others just go ahead.

jacob

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#67278

FromBen Bacarisse <ben.usenet@bsb.me.uk>
Date2015-08-13 13:32 +0100
Message-ID<87oaib4bdo.fsf@bsb.me.uk>
In reply to#67266
jacobnavia <jacob@jacob.remcomp.fr> writes:

> Le 13/08/2015 00:28, fl a écrit :
<snip>
>> How to read a data file whose size is unknown in C?
>>
>> The data file could be a .img file.
>>
>> I thought about fseek(), etc., but I was not sure at all and didn't say
>> anything about it. Whether is it about some function on the end of the file?
<snip>
> If you use fseek to go to the end of the file, then ftell to store the
> size, you can get the length of the file on disc.
>
> This solution will work in the following systems:
>
> Android
> iOs (Apple)
> Linux
> Mac OS X
> All other POSIX systems
> Windows (all versions)
> MSDOS
>
> This makes for a very portable solution that can break in some odd
> systems. If your system is in the list above and you do not care about
> others just go ahead.

But it fails on most (all?) of those systems if the file is a pipe or
some other kinds of special files.  It's important to point that out
because it can seriously harm the usefulness of a tool if can only work
with seekable files.  It's probably not important to the OP, but anyone
using fseek to get a file's size should know all the consequences of
that design.

-- 
Ben.

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#67280

Fromjacobnavia <jacob@jacob.remcomp.fr>
Date2015-08-13 14:49 +0200
Message-ID<mqi3ko$rr7$1@dont-email.me>
In reply to#67278
Le 13/08/2015 14:32, Ben Bacarisse a écrit :
> jacobnavia <jacob@jacob.remcomp.fr> writes:
>
>> Le 13/08/2015 00:28, fl a écrit :
> <snip>
>>> How to read a data file whose size is unknown in C?
>>>
>>> The data file could be a .img file.
>>>
>>> I thought about fseek(), etc., but I was not sure at all and didn't say
>>> anything about it. Whether is it about some function on the end of the file?
> <snip>
>> If you use fseek to go to the end of the file, then ftell to store the
>> size, you can get the length of the file on disc.
>>
>> This solution will work in the following systems:
>>
>> Android
>> iOs (Apple)
>> Linux
>> Mac OS X
>> All other POSIX systems
>> Windows (all versions)
>> MSDOS
>>
>> This makes for a very portable solution that can break in some odd
>> systems. If your system is in the list above and you do not care about
>> others just go ahead.
>
> But it fails on most (all?) of those systems if the file is a pipe or
> some other kinds of special files.  It's important to point that out
> because it can seriously harm the usefulness of a tool if can only work
> with seekable files.  It's probably not important to the OP, but anyone
> using fseek to get a file's size should know all the consequences of
> that design.
>

Well, that's true.

So, the universally accepted advice:

"Just read all the file, then you know its size" is ALSO wrong!!!

You just keep reading the pipe and then... well, you can't start from 
scratch!

Please be reasonable Ben, thanks

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#67283

FromRichard Heathfield <rjh@cpax.org.uk>
Date2015-08-13 14:05 +0100
Message-ID<mqi4j4$c5$1@dont-email.me>
In reply to#67280
On 13/08/15 13:49, jacobnavia wrote:
> Le 13/08/2015 14:32, Ben Bacarisse a écrit :

<snip>

>> [...] It's probably not important to the OP, but anyone
>> using fseek to get a file's size should know all the consequences of
>> that design.
>>
>
> Well, that's true.

Aye.

> So, the universally accepted advice:

Hang on a sec - you're over-simplifying...

>
> "Just read all the file, then you know its size" is ALSO wrong!!!

...and yes, that advice is indeed also wrong, but it's not universally 
accepted advice. For one thing, you don't accept it! (And you're right 
not to.) But of course there are others, too, who don't accept it.

Of course, the fseek/ftell method does work in many situations, and so 
does the "read the file and count as you go" method. But *each* of them 
can fail in some situations, and it's wise to know what those situations 
are, so that we can make a reasoned choice based on our own 
circumstances. The OP, for example, simply wanted to know how big a .img 
file is, probably on his own Windows or Linux machine. He could probably 
use fseek/ftell; he could probably read and count; he could almost 
certainly use an OS call. Any of these will probably work. The 
discussion has been focused not on whether these techniques will 
probably work but on the fact that they are not *guaranteed* to work in 
all situations. That, it seems to me, is a reasonable thing to point 
out, especially as so many people appear to think that fseek/ftell is 
somehow blessed as a special, magical technique - which, of course, it 
isn't.

> You just keep reading the pipe and then... well, you can't start from
> scratch!

It's the wrong question. The pipe is a good metaphor, actually (although 
arguing from analogy is always dangerous). If I go to my kitchen sink 
and turn my tap (faucet, for our crosspondian cousins), water flows 
through the pipe and out of the tap. If I find myself asking /how much/ 
water might flow out, then - well, okay, it's a reasonable question for 
an enquiring mind to pose, but when we think it through, we realise that 
there is no realistic way to find out that information.

> Please be reasonable Ben, thanks

I think he /is/ being reasonable. But perhaps the most important point 
we can make here is: *however* we find out the length of the file 
(assuming we can), we should wrap that technique up into a function of 
our own, so that we don't pollute the rest of the source with code that 
might not work when we move the code to another platform. Let's leave 
ourselves with a *small* editing job, not a *huge* editing job.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within

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#67292

FromBen Bacarisse <ben.usenet@bsb.me.uk>
Date2015-08-13 14:50 +0100
Message-ID<87d1yr47r7.fsf@bsb.me.uk>
In reply to#67280
jacobnavia <jacob@jacob.remcomp.fr> writes:

> Le 13/08/2015 14:32, Ben Bacarisse a écrit :
>> jacobnavia <jacob@jacob.remcomp.fr> writes:
>>
>>> Le 13/08/2015 00:28, fl a écrit :
>> <snip>
>>>> How to read a data file whose size is unknown in C?
>>>>
>>>> The data file could be a .img file.
>>>>
>>>> I thought about fseek(), etc., but I was not sure at all and didn't say
>>>> anything about it. Whether is it about some function on the end of the file?
>> <snip>
>>> If you use fseek to go to the end of the file, then ftell to store the
>>> size, you can get the length of the file on disc.
>>>
>>> This solution will work in the following systems:
>>>
>>> Android
>>> iOs (Apple)
>>> Linux
>>> Mac OS X
>>> All other POSIX systems
>>> Windows (all versions)
>>> MSDOS
>>>
>>> This makes for a very portable solution that can break in some odd
>>> systems. If your system is in the list above and you do not care about
>>> others just go ahead.
>>
>> But it fails on most (all?) of those systems if the file is a pipe or
>> some other kinds of special files.  It's important to point that out
>> because it can seriously harm the usefulness of a tool if can only work
>> with seekable files.  It's probably not important to the OP, but anyone
>> using fseek to get a file's size should know all the consequences of
>> that design.
>>
>
> Well, that's true.
>
> So, the universally accepted advice:
>
> "Just read all the file, then you know its size" is ALSO wrong!!!
>
> You just keep reading the pipe and then... well, you can't start from
> scratch!
>
> Please be reasonable Ben, thanks

In what way an I being unreasonable?  I tried hard to phrase what I said
in the most gentle and reasonable way I could find.

-- 
Ben.

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#67303

FromKeith Thompson <kst-u@mib.org>
Date2015-08-13 09:14 -0700
Message-ID<lnvbcjb1xa.fsf@kst-u.example.com>
In reply to#67280
jacobnavia <jacob@jacob.remcomp.fr> writes:
> Le 13/08/2015 14:32, Ben Bacarisse a écrit :
[...]
>> But it fails on most (all?) of those systems if the file is a pipe or
>> some other kinds of special files.  It's important to point that out
>> because it can seriously harm the usefulness of a tool if can only work
>> with seekable files.  It's probably not important to the OP, but anyone
>> using fseek to get a file's size should know all the consequences of
>> that design.
>>
>
> Well, that's true.
>
> So, the universally accepted advice:
>
> "Just read all the file, then you know its size" is ALSO wrong!!!
>
> You just keep reading the pipe and then... well, you can't start from 
> scratch!

Who says you need to start from scratch?

You can read from a pipe until you get an end-of-file indication.
With judicious use of realloc(), you can store all the data from the
pipe in an allocated array.  You *can't* do the same thing by using
fstat(), or fseek/ftell.  If the pipe never reports end-of-file,
hopefully you'll have some way to handle that.

Similar considerations apply to other things that act like files
but are not ordinary fixed-size disk files.  For example, I can
read 1898 bytes from /proc/stat on my system, but the file system
reports its size as 0 (and fseek() appears to work without error,
but ftell() then returns 0, which is odd).

I can type "view /proc/stat" ("view" is a read-only version of
the vi/vim text editor), and it works.  Apparently vim is clever
enough not to assume that either fstat or fseek/ftell reports an
accurate size.

-- 
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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#67311

FromJames Kuyper <jameskuyper@verizon.net>
Date2015-08-13 12:42 -0400
Message-ID<mqihap$igv$1@dont-email.me>
In reply to#67280
On 08/13/2015 08:49 AM, jacobnavia wrote:
...
> So, the universally accepted advice:
> 
> "Just read all the file, then you know its size" is ALSO wrong!!!

That's not universally accepted, primarily because it is, as you point
out, wrong.

The right solution, which is NOT universally accepted, is to accept the
fact that C itself provides no solution to this problem, and look for
OS-specific alternatives. "Read all of the file" might be the only thing
that works on some systems, and won't work at all on others.
"fseek()+ftell()" might work on some, but not others. Calling "stat()"
works on all Unix-like systems, as far as I know, and similar functions
exist on most operating systems that are not Unix-like. It's annoying,
but the C standard is intended to implementable even on systems so
peculiar that nothing equivalent to stat() could meaningfully exist on
those systems.
-- 
James Kuyper

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#67299

FromKen Brody <kenbrody@spamcop.net>
Date2015-08-13 10:56 -0400
Message-ID<mqib31$pmt$1@dont-email.me>
In reply to#67266
On 8/13/2015 6:38 AM, jacobnavia wrote:
> Le 13/08/2015 00:28, fl a écrit :
>> Hi,
>>
>> I had a test and I don't know what is the catch:
[...]
>> I thought about fseek(), etc., but I was not sure at all and didn't say
>> anything about it. Whether is it about some function on the end of the file?
[...]
> If you use fseek to go to the end of the file, then ftell to store the size,
> you can get the length of the file on disc.
>
> This solution will work in the following systems:
[...]

That's what I use.  However, I code for the POSIX world, and not the ANSI C 
world, which allows me to make assumptions that ANSI C, as discussed here, 
would not.

Maybe someone should propose comp.lang.c.posix?

-- 
Kenneth Brody

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#67304

FromKeith Thompson <kst-u@mib.org>
Date2015-08-13 09:16 -0700
Message-ID<lnr3n7b1ue.fsf@kst-u.example.com>
In reply to#67299
Ken Brody <kenbrody@spamcop.net> writes:
> On 8/13/2015 6:38 AM, jacobnavia wrote:
[...]
>> If you use fseek to go to the end of the file, then ftell to store the size,
>> you can get the length of the file on disc.
>>
>> This solution will work in the following systems:
> [...]
>
> That's what I use.  However, I code for the POSIX world, and not the ANSI C 
> world, which allows me to make assumptions that ANSI C, as discussed here, 
> would not.

Why don't you use stat/fstat?

> Maybe someone should propose comp.lang.c.posix?

comp.unix.programmer is probably close enough.

-- 
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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#67305

FromLőrinczy Zsigmond <zsiga@nospam.for.me>
Date2015-08-13 18:12 +0200
Message-ID<mqifol$7pj$1@speranza.aioe.org>
In reply to#67304
>> That's what I use.  However, I code for the POSIX world, and not the ANSI C
>> world, which allows me to make assumptions that ANSI C, as discussed here,
>> would not.
>
> Why don't you use stat/fstat?

Some possible reason: socket, pipe, character-device

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#67314

FromJames Kuyper <jameskuyper@verizon.net>
Date2015-08-13 12:50 -0400
Message-ID<mqihp1$k5a$1@dont-email.me>
In reply to#67305
On 08/13/2015 12:12 PM, Lőrinczy Zsigmond wrote:
>>> That's what I use.  However, I code for the POSIX world, and not the ANSI C
>>> world, which allows me to make assumptions that ANSI C, as discussed here,
>>> would not.
>>
>> Why don't you use stat/fstat?
> 
> Some possible reason: socket, pipe, character-device

The st_mode field in struct stat which is filled in by calling
stat()/fstat() can tell you whether one of those possibilities is
relevant, so your answer sound to me like a reason FOR using
stat()/fstat(), rather than AGAINST.
-- 
James Kuyper

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