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Groups > comp.lang.c > #111865

Re: sizeof environment variables array = 1?

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: sizeof environment variables array = 1?
Date 2017-06-08 15:12 -0700
Organization None to speak of
Message-ID <lnink6i0x9.fsf@kst-u.example.com> (permalink)
References (2 earlier) <ohbt7i$jm2$2@dont-email.me> <ohbuk2$p49$1@dont-email.me> <ohc2ha$7n2$1@dont-email.me> <ohcbeq$1cbo$1@gioia.aioe.org> <ohcfh3$m23$2@dont-email.me>

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DFS <nospam@dfs.com> writes:
> On 6/8/2017 4:18 PM, jak wrote:
>> Why don't you use the getenv fuction? It comes with standard libraries 
>> (stdio.h).
>
> Thanks for the hint.
>
> What I was wanting to do was check the Windows Path to see if they had 
> the GNUWin32 packages installed.  It would be rare, but if they do have 
> them I can use the 'file' command, same as on Linux.
>
> On Linux I don't think I'll need to check the environ vars; the 'file' 
> command is installed by default as far as I know.
>
> I'll try getenv here on Windows.
>
> Edit:  it's a few lines.
>
> if (strstr(getenv("Path"),"string") != NULL)
> printf("string found in Path\n");
> else
> printf("string not found in path\n");

You're still trying to use the "file" command for this?

There is no clear distinction between text files and binary files.
Invoking the "file" command (which may or may not be available) on
a file will not reliably tell you whether a file is text or binary.
The output of the "file" command is intended for human consumption,
and is not designed to be parseable (unless you ask it for the MIME
type, but even that is likely to be unsuitable for your purpose).

I think you have a classic XY problem <http://xyproblem.info/>.
Your underlying problem is to determine whether an input file is
valid for your program.  You've decided that the first step in
solving that problem is to determine whether the file is text or
binary, and you've been on a wild goose chase figuring out how to
do that.

Instead, I strongly suggest you define what constitutes valid input
for your program, and check for that.

What characters are acceptable?  Printable ASCII characters?
ASCII control characters?  Non-ASCII accented letters?  If the file
turns out to be valid, will you read it as text?  Are multibyte
characters acceptable?  Is there a maximum acceptable line length?
And so on.

For example, if I feed a binary file named "c.c" to gcc, it doesn't
check whether it's text or binary; it simply tries to parse it as
C source code and prints error messages if it fails.

-- 
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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sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 11:13 -0400
  Re: sizeof environment variables array = 1? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-06-08 11:25 -0400
    Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 09:34 -0700
      Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 13:14 -0400
        Re: sizeof environment variables array = 1? jameskuyper@verizon.net - 2017-06-08 10:51 -0700
  Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-08 16:56 +0100
    Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 12:18 -0400
      Re: sizeof environment variables array = 1? scott@slp53.sl.home (Scott Lurndal) - 2017-06-08 16:35 +0000
      Re: sizeof environment variables array = 1? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-06-08 12:43 -0400
        Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 13:49 -0400
          Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-08 13:58 -0400
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 14:45 -0400
          Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 12:10 -0700
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-09 11:21 -0400
            Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 16:23 +0100
              Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 11:48 -0400
                Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 16:53 +0100
                Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 12:18 -0400
                Re: sizeof environment variables array = 1? Richard Heathfield <rjh@cpax.org.uk> - 2017-06-09 17:28 +0100
                Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-09 09:12 -0700
              Re: sizeof environment variables array = 1? "Patrick.Schluter" <Patrick.Schluter@free.fr> - 2017-06-10 09:28 +0200
          Re: sizeof environment variables array = 1? jak <please@nospam.tnx> - 2017-06-08 22:18 +0200
            Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-08 17:31 -0400
              Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 15:12 -0700
                Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-09 11:21 -0400
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-09 16:39 +0100
                Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-10 07:26 +0100
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-10 13:21 +0100
                Re: sizeof environment variables array = 1? gordonb.q80bx@burditt.org (Gordon Burditt) - 2017-06-10 17:32 -0500
                Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-11 01:01 +0100
                Re: sizeof environment variables array = 1? luser droog <luser.droog@gmail.com> - 2017-06-11 01:28 -0700
                Re: sizeof environment variables array = 1? raltbos@xs4all.nl (Richard Bos) - 2017-06-17 18:38 +0000
                Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-09 08:41 -0700
                Re: sizeof environment variables array = 1? "James R. Kuyper" <jameskuyper@verizon.net> - 2017-06-09 11:50 -0400
                Re: sizeof environment variables array = 1? raltbos@xs4all.nl (Richard Bos) - 2017-06-17 18:37 +0000
                Re: sizeof environment variables array = 1? DFS <nospam@dfs.com> - 2017-06-18 09:11 -0400
          Re: sizeof environment variables array = 1? "Patrick.Schluter" <Patrick.Schluter@free.fr> - 2017-06-10 09:19 +0200
      Re: sizeof environment variables array = 1? Robert Wessel <robertwessel2@yahoo.com> - 2017-06-08 12:44 -0500
    Re: sizeof environment variables array = 1? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-08 18:01 +0100
      Re: sizeof environment variables array = 1? Gareth Owen <gwowen@gmail.com> - 2017-06-08 18:45 +0100
    Re: sizeof environment variables array = 1? Keith Thompson <kst-u@mib.org> - 2017-06-08 11:51 -0700

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