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Groups > comp.lang.c > #111451

Re: what does # mean?

From James Kuyper <jameskuyper@verizon.net>
Newsgroups comp.lang.c
Subject Re: what does # mean?
Date 2017-06-03 23:08 -0400
Organization A noiseless patient Spider
Message-ID <ogvtcl$e1f$1@dont-email.me> (permalink)
References <ogtotj$r7b$1@dont-email.me>

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On 06/03/2017 03:39 AM, T wrote:
> Hi All,
> 
> I don't understand C.  I am trying to find something
> in some source code.  What does "#" mean as in

There is one context in which # has a specific meaning of it's own. This
isn't that context.

> #include "check_events.h"
> 
> and
> 
> #ifdef HAVE_LIBNOTIFY7
>      notification = notify_notification_new(summary, body, 
> "dialog-warning");
> #else
>      notification = notify_notification_new(summary, body, 
> "dialog-warning", NULL);
> #endif /* HAVE_LIBNOTIFY7 */

C has something called pre-processing directives. Every single
pre-processing directive starts with "#", and every line where the first
non-whitespace character is a "#" is a pre-processing directive (that's
true because, if # is followed by anything other than one of the
standard-defined pre-processing directives, it qualifies as a
"non-directive" - and, confusingly enough, a non-directive is considered
to be one kind of pre-processing directive. (6.10p1).
I'm not the one who chose to name those concepts that way, and I make no
attempt to justify choosing those names - I'm just telling you what the
standard says.

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Thread

what does # mean? T <T@invalid.invalid> - 2017-06-03 00:39 -0700
  Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-03 10:06 +0200
    Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 01:25 -0700
      Re: what does # mean? Leon Taylor <leontaylor476@gmail.com> - 2017-06-03 03:41 -0700
      Re: what does # mean? Keith Thompson <kst-u@mib.org> - 2017-06-03 09:03 -0700
        Re: what does # mean? bartc <bc@freeuk.com> - 2017-06-03 17:11 +0100
          Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 13:56 -0700
  Re: what does # mean? Jerry Stuckle <jstucklex@attglobal.net> - 2017-06-03 09:24 -0400
    Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 13:52 -0700
    Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 13:55 -0700
      Re: what does # mean? Jerry Stuckle <jstucklex@attglobal.net> - 2017-06-04 18:19 -0400
        Re: what does # mean? T <T@invalid.invalid> - 2017-06-05 01:54 -0700
  Re: what does # mean? Keith Thompson <kst-u@mib.org> - 2017-06-03 09:05 -0700
    Re: what does # mean? gazelle@shell.xmission.com (Kenny McCormack) - 2017-06-03 16:18 +0000
      Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-03 18:22 +0200
        Re: what does # mean? gazelle@shell.xmission.com (Kenny McCormack) - 2017-06-03 16:30 +0000
          Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-03 19:18 +0200
            Re: what does # mean? gazelle@shell.xmission.com (Kenny McCormack) - 2017-06-03 18:03 +0000
    Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 13:59 -0700
      Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-03 23:30 +0200
        Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 14:35 -0700
          Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-03 23:55 +0200
            Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 15:30 -0700
              Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-04 00:36 +0200
                Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 16:12 -0700
                Re: what does # mean? Ian Collins <ian-news@hotmail.com> - 2017-06-04 11:17 +1200
                Re: what does # mean? GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-04 01:23 +0200
      Re: what does # mean? Keith Thompson <kst-u@mib.org> - 2017-06-03 19:15 -0700
        Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 19:27 -0700
          Re: what does # mean? Manfred <noname@invalid.add> - 2017-06-04 19:09 +0200
            Re: what does # mean? T <T@invalid.invalid> - 2017-06-05 01:56 -0700
          Re: what does # mean? Keith Thompson <kst-u@mib.org> - 2017-06-04 13:51 -0700
            Re: what does # mean? T <T@invalid.invalid> - 2017-06-05 01:57 -0700
  Re: what does # mean? James Kuyper <jameskuyper@verizon.net> - 2017-06-03 23:08 -0400
    Re: what does # mean? T <T@invalid.invalid> - 2017-06-03 20:53 -0700
      Re: what does # mean? John Bode <jfbode1029@gmail.com> - 2017-06-05 12:44 -0700
        Re: what does # mean? T <T@invalid.invalid> - 2017-06-05 14:52 -0700
  Re: what does # mean? T <T@invalid.invalid> - 2017-06-05 03:00 -0700

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