Re: Synthetic 'unless' keyword

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: Synthetic 'unless' keyword
Date	2016-08-04 08:45 -0700
Organization	None to speak of
Message-ID	<lnpopo1qsj.fsf@kst-u.example.com> (permalink)
References	<e0gh38F2552U1@mid.uni-berlin.de> <mstorkamp-73C8D2.07014904082016@88-209-239-213.giganet.hu>

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Mark Storkamp <mstorkamp@yahoo.com> writes:
[...]
> 'unless' goes back at least as far as BCPL, and I've used it like you 
> have a few times when it seemed appropriate. I don't understand why it 
> wasn't put into C, except that it isn't truly necessary (but then by 
> that argument, neither is the 'for' loop)

The difference, I think, is that `unless` is *trivially* unnecessary.
You can write the equivalent of a `for` loop using `while`, but it's
verbose and easy to get wrong.  `unless` just adds an implicit `!`.

-- 
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"

Thread

Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 09:44 +0000
  Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-04 12:21 +0200
  Re: Synthetic 'unless' keyword Mark Storkamp <mstorkamp@yahoo.com> - 2016-08-04 07:01 -0500
    Re: Synthetic 'unless' keyword bert <bert.hutchings@btinternet.com> - 2016-08-04 05:42 -0700
    Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 08:45 -0700
      Re: Synthetic 'unless' keyword Philip Lantz <prl@canterey.us> - 2016-08-04 21:55 -0700
      Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 10:08 +0100
    Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-05 01:17 -0700
      Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 10:01 +0100
        Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-05 04:34 -0700
      Re: Synthetic 'unless' keyword Mark Storkamp <mstorkamp@yahoo.com> - 2016-08-05 09:37 -0500
        Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-06 02:28 -0700
  Re: Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 13:38 +0000
  Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-04 15:04 +0100
  Re: Synthetic 'unless' keyword mark.bluemel@gmail.com - 2016-08-04 07:06 -0700
  Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 08:52 -0700
    Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-04 09:45 -0700
      Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 10:23 -0700
        Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-04 19:39 +0100
          Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-04 12:02 -0700
            Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-04 20:33 +0100
            Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-04 20:42 +0100
              Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-05 13:14 +0200
                Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-05 12:41 +0100
    Re: Synthetic 'unless' keyword mark.bluemel@gmail.com - 2016-08-05 00:53 -0700
  Re: Synthetic 'unless' keyword Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-04 16:43 -0400
    Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-05 13:16 +0200
  Re: Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 23:16 +0000
    Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-05 00:35 +0100
    Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-04 20:13 -0700
    Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-05 04:57 -0700
      Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 13:15 +0100
        Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-18 08:11 -0700
          Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-18 16:36 +0100
            Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-18 10:20 -0700
  Re: Synthetic 'unless' keyword Paul N <gw7rib@aol.com> - 2016-08-07 12:56 -0700

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