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Re: what does # mean?

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On 06/05/2017 12:44 PM, John Bode wrote:
> On Saturday, June 3, 2017 at 10:53:59 PM UTC-5, T wrote:
>> On 06/03/2017 08:08 PM, James Kuyper wrote:
>>> 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.
>>>
>>
>> Thank you!  I thought it was a comment.
> 
> For reference, there are two sets of comment delimiters in C.  There is the
> pair of delimiters /* and */ - anything that appears between them is a
> comment:
> 
>      /* This is a comment */
> 
>      /**
>       * So is this
>       */
> 
> There's also the single delimiter // - anything between that and the next
> newline is a comment:
> 
>      // the rest of this line is a comment
> 
> Comments in C do not "nest" - You can't do something like
> 
>      /* some text /* some more text */ yet more text */
> 
> The compiler will consider the first */ it sees to end the comment, and
> everything after that will be treated as source code, which will lead
> to a compile error.
> 

Thank you!

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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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