Re: How to determine if file is binary or text?

From	jak <please@nospam.tnx>
Newsgroups	comp.lang.c
Subject	Re: How to determine if file is binary or text?
Date	2017-06-09 08:46 +0200
Organization	Aioe.org NNTP Server
Message-ID	<ohdg7i$tc9$1@gioia.aioe.org> (permalink)
References	(2 earlier) <oh9tla$p61$1@dont-email.me> <87poefe8h1.fsf@bsb.me.uk> <oha5b6$e96$2@dont-email.me> <ohbqob$ep$1@dont-email.me> <ohcjon$5su$5@dont-email.me>

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Il 09/06/2017 00:43, DFS ha scritto:
> On 6/8/2017 11:33 AM, Michael Forsythe wrote:
>
>
>> Others have mentioned popen, and you've already discovered the pain
>> that comes with that. At least on my systems, file comes with the
>> helpful libmagic library. If you can link against that:
>>
> <snip code>
>
>
>> The library also has magic_buffer in case you've already loaded the
>> file into memory.
>>
>> Of course, as others have already said, you probably want to do
>> some processing with the file after you've loaded it (treat it as
>> a configuration file, extract all email addresses, treat it as a
>> sequence of SAN chess moves, whatever). If so, you're probably
>> better off treating the file as a bunch of bytes and attempting to
>> specifically validate for whatever you're going to use the file
>> for.
>
> Thanks for the suggestions.  I got the _popen/pipes working on Windows,
> but I'm making my code cross-platform (Windows and Linux), and the above
> looks like more fun on Linux.
>
>
Your domain is not sufficiently clear: you want to check if a file 
contains binary data or text data. My question is: text or ascii text?
If your answer is ascii text, the only way is to open the file in binary 
mode and test each byte with the macro / function isascii (); this with 
respect to portability. But if you want to check if the file contains 
just some generic text, then you can't because the file might contain 
text in any format other than the ascii, such as utf8, utf16, utf32 and 
so on. Unfortunately, these last encodings use the value of a byte in full.

Thread

How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-07 14:40 -0400
  Re: How to determine if file is binary or text? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-07 20:46 +0200
  Re: How to determine if file is binary or text? bartc <bc@freeuk.com> - 2017-06-07 19:58 +0100
  Re: How to determine if file is binary or text? scott@slp53.sl.home (Scott Lurndal) - 2017-06-07 19:05 +0000
  Re: How to determine if file is binary or text? supercat@casperkitty.com - 2017-06-07 12:10 -0700
  Re: How to determine if file is binary or text? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-07 16:25 -0400
  Re: How to determine if file is binary or text? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-06-07 21:44 +0000
    Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-07 18:14 -0400
      Re: How to determine if file is binary or text? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-08 00:23 +0200
        Re: How to determine if file is binary or text? Robert Wessel <robertwessel2@yahoo.com> - 2017-06-08 00:11 -0500
          Re: How to determine if file is binary or text? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-08 15:14 +0200
            Re: How to determine if file is binary or text? Robert Wessel <robertwessel2@yahoo.com> - 2017-06-08 11:06 -0500
          Re: How to determine if file is binary or text? raltbos@xs4all.nl (Richard Bos) - 2017-06-17 18:28 +0000
      Re: How to determine if file is binary or text? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-07 23:30 +0100
        Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-07 20:26 -0400
          Re: How to determine if file is binary or text? bartc <bc@freeuk.com> - 2017-06-08 01:30 +0100
            Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-07 23:50 -0400
              Re: How to determine if file is binary or text? mark.bluemel@gmail.com - 2017-06-08 02:13 -0700
                Re: How to determine if file is binary or text? mark.bluemel@gmail.com - 2017-06-08 04:05 -0700
                Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-08 09:21 -0400
                Re: How to determine if file is binary or text? Ike Naar <ike@iceland.freeshell.org> - 2017-06-08 14:19 +0000
                Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-08 12:07 -0400
                Re: How to determine if file is binary or text? scott@slp53.sl.home (Scott Lurndal) - 2017-06-08 16:14 +0000
                Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-08 12:37 -0400
                Re: How to determine if file is binary or text? scott@slp53.sl.home (Scott Lurndal) - 2017-06-08 16:54 +0000
                Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-08 13:14 -0400
                An old version of what??? (Was: How to determine if file is binary or text?) gazelle@shell.xmission.com (Kenny McCormack) - 2017-06-09 17:13 +0000
              Re: How to determine if file is binary or text? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-08 11:15 +0100
          Re: How to determine if file is binary or text? scott@slp53.sl.home (Scott Lurndal) - 2017-06-08 12:49 +0000
          Re: How to determine if file is binary or text? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-06-08 14:01 +0000
          Re: How to determine if file is binary or text? Michael Forsythe <forsythe@example.com> - 2017-06-08 15:33 +0000
            Re: How to determine if file is binary or text? DFS <nospam@dfs.com> - 2017-06-08 18:43 -0400
              Re: How to determine if file is binary or text? jak <please@nospam.tnx> - 2017-06-09 08:46 +0200
      Re: How to determine if file is binary or text? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-07 19:23 -0400
      Re: How to determine if file is binary or text? Barry Schwarz <schwarzb@dqel.com> - 2017-06-07 16:50 -0700
      Re: How to determine if file is binary or text? "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-06-08 15:51 +0200
  Re: How to determine if file is binary or text? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-06-07 17:17 -0600
    Re: How to determine if file is binary or text? Keith Thompson <kst-u@mib.org> - 2017-06-07 19:21 -0700
      Re: How to determine if file is binary or text? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-06-07 21:37 -0600
  Re: How to determine if file is binary or text? Noob <root@127.0.0.1> - 2017-06-08 08:40 +0200
  Re: How to determine if file is binary or text? gordonb.t9rom@burditt.org (Gordon Burditt) - 2017-06-08 12:03 -0500

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