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Re: Shortened form of condition

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: Shortened form of condition
Date 2015-11-09 19:35 +0000
Organization A noiseless patient Spider
Message-ID <87oaf3ney7.fsf@bsb.me.uk> (permalink)
References <b6b2a9ec-4944-4e34-95e1-779161509469@googlegroups.com> <62775b24-22c8-4b78-85ca-6ca99456f2c5@googlegroups.com>

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Alla _ <modelling.data@gmail.com> writes:

> Thank you for your explanations. I am sorry but Ben and James suggested
> the ones that are close to my interpretation, while Barry has a different one.
> I don't have problems with reading bool values and their opposites, but I 
> do have an issue with controlling expressions and the way bool values are used
> in them.
>
> 1) Ben and James suggest (it is close to how I have read the condition of 
> while loop), if I am not mistaken, that because end_of_text had been initially
> set to false, i.e. to 0, then "while (!end_of_text)" means 
> "while(end_of_text is true, i.e. equals 1)".

I don't see how you think I said that!  It means exactly the opposite.
All of these are the same in your example program (except for some of
them being bad style):

  while (!end_of_text) ...
  while (!end_of_text == 1) ...
  while (!end_of_text != 0) ...
  while (end_of_text == 0) ...
  while (end_of_text != 1) ...

> Hence, when the loop is first encountered, the controlling expression of 
> end_of_text is 1 (!end_of_text).

There some deep misunderstanding here.  The controlling expression of
the while loop is

  !end_of_text

and the phrase "the controlling expression of end_of_text is 1" does not
make any sense to me.

You seem to be happier with 'if' statements so, at the risk of confusing
you more, the while loop is really doing this:

  loop:
    if (!end_of_text) {
        read_line(text);
        
        if (text[0] == '\0')
            end_of_text = true;
        else
            total_words += count_words (text);

        goto loop;
    }

If this baffles you, just bin the message and ignore anything else I say.

<snip>
-- 
Ben.

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Thread

Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-09 06:23 -0800
  Re: Shortened form of condition Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-09 14:44 +0000
  Re: Shortened form of condition James Kuyper <jameskuyper@verizon.net> - 2015-11-09 10:17 -0500
  Re: Shortened form of condition Barry Schwarz <schwarzb@dqel.com> - 2015-11-09 09:20 -0800
  Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-09 10:11 -0800
    Re: Shortened form of condition Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-09 10:35 -0800
      Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-10 00:14 -0800
        Re: Shortened form of condition Barry Schwarz <schwarzb@dqel.com> - 2015-11-10 03:04 -0800
          Re: Shortened form of condition glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-10 21:42 +0000
        Re: Shortened form of condition Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-10 11:13 +0000
          Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-10 07:58 -0800
            Re: Shortened form of condition Richard Heathfield <rjh@cpax.org.uk> - 2015-11-10 17:06 +0000
            Re: Shortened form of condition James Kuyper <jameskuyper@verizon.net> - 2015-11-10 12:11 -0500
              Re: Shortened form of condition James Kuyper <jameskuyper@verizon.net> - 2015-11-10 14:01 -0500
          Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-10 08:30 -0800
            Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-10 09:07 -0800
              Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-10 09:29 -0800
                Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-10 11:02 -0800
                Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-10 11:33 -0800
                Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-11 00:28 -0800
                Re: Shortened form of condition Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-11 16:05 +0000
                Re: Shortened form of condition glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-12 09:29 +0000
                Re: Shortened form of condition Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-12 10:56 +0000
                Re: Shortened form of condition Richard Heathfield <rjh@cpax.org.uk> - 2015-11-11 16:24 +0000
                Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-11 08:53 -0800
                Re: Shortened form of condition Richard Heathfield <rjh@cpax.org.uk> - 2015-11-11 16:59 +0000
                Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-11 06:42 -0800
                Re: Shortened form of condition Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-10 14:04 -0500
              Re: Shortened form of condition Barry Schwarz <schwarzb@dqel.com> - 2015-11-10 10:43 -0800
    Re: Shortened form of condition James Kuyper <jameskuyper@verizon.net> - 2015-11-09 13:44 -0500
    Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-09 10:57 -0800
      Re: Shortened form of condition Philip Lantz <prl@canterey.us> - 2015-11-10 01:52 -0800
    Re: Shortened form of condition Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-09 19:35 +0000
      Re: Shortened form of condition Keith Thompson <kst-u@mib.org> - 2015-11-09 11:52 -0800
  Re: Shortened form of condition Alla _ <modelling.data@gmail.com> - 2015-11-10 00:33 -0800
    Re: Shortened condition Richard Heathfield <rjh@cpax.org.uk> - 2015-11-10 09:00 +0000
  Re: Shortened form of condition Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-10 16:01 -0800

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