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Groups > comp.lang.c > #102243

Re: while loop condition doesn't work

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: while loop condition doesn't work
Date 2017-01-20 17:54 +0100
Organization A noiseless patient Spider
Message-ID <o5tf8a$lpn$1@dont-email.me> (permalink)
References (1 earlier) <871svxdiu9.fsf@bsb.me.uk> <e9b02777-9542-4e5b-bbf7-885c9bbcb5da@googlegroups.com> <87pojhbw2h.fsf@bsb.me.uk> <d4616907-128c-442d-b29e-82bf47b4e83d@googlegroups.com> <o5tcfb$ap3$1@dont-email.me>

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On 20/01/17 17:06, Richard Heathfield wrote:
> 
>     /* if we're just at a field boundary, we
>        want to move to just past that boundary.
>        If we're at the end of the string,
>        then two things happen: (1) we can't be
>        sure that it's legal to move past the '\0'
>        AND (2) there is in any case nothing more
>        to convert.
> 
>        So if we're not at '\0', we want ptr to
>        point to not_converted + 1. Otherwise, we
>        want ptr to point to not_converted (which will
>        terminate the loop).
> 
>        In C, the result of a condition is either 0
>        (false), or 1 (true), and this happens to map
>        precisely onto what we want. So we can do this:
>      */
> 
>     ptr = not_converted + (*not_converted != '\0');
> 

And how is that better than:

	if (*not_converted != '\0') {
		ptr = not_converted + 1;
	} else {
		ptr = not_converted;
	}

Rather than writing a nice, clear explanation in comments followed by
code with a completely different structure, why not simply write the
code that follows the nice, clear explanation?  Then you can also skip
that part of the comment.

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Thread

while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 01:24 -0800
  Re: while loop condition doesn't work mark.bluemel@gmail.com - 2017-01-20 03:29 -0800
  Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-20 12:19 +0000
    Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 05:12 -0800
      Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-20 13:17 +0000
        Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 05:20 -0800
        Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-20 15:07 +0000
    Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 05:31 -0800
      Re: while loop condition doesn't work Manfred <noname@invalid.add> - 2017-01-20 15:23 +0100
      Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-20 15:16 +0000
        Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 07:45 -0800
          Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-20 16:06 +0000
            Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 08:37 -0800
            Re: while loop condition doesn't work David Brown <david.brown@hesbynett.no> - 2017-01-20 17:54 +0100
              Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-20 17:04 +0000
                Re: while loop condition doesn't work David Brown <david.brown@hesbynett.no> - 2017-01-20 19:08 +0100
                Re: while loop condition doesn't work Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-30 12:51 -0800
                Re: while loop condition doesn't work Keith Thompson <kst-u@mib.org> - 2017-01-30 14:09 -0800
                Re: while loop condition doesn't work supercat@casperkitty.com - 2017-01-30 14:57 -0800
                Re: while loop condition doesn't work Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-01 21:31 -0800
                Re: while loop condition doesn't work Keith Thompson <kst-u@mib.org> - 2017-02-02 10:01 -0800
                Re: while loop condition doesn't work Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-04 00:22 -0800
              Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-20 19:12 +0000
                Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-23 10:54 +0000
            Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 23:22 -0800
              Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-23 11:02 +0000
            Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-21 01:22 -0800
              Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-21 11:00 +0000
                Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-21 08:35 -0800
                Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-21 17:17 +0000
                Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-21 09:32 -0800
          Re: while loop condition doesn't work Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-20 19:16 +0000
            Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-23 11:03 +0000
    Re: while loop condition doesn't work David Brown <david.brown@hesbynett.no> - 2017-01-20 14:34 +0100
      Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 07:40 -0800
        Re: while loop condition doesn't work Richard Heathfield <rjh@cpax.org.uk> - 2017-01-20 15:47 +0000
          Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 08:26 -0800
            Re: while loop condition doesn't work David Brown <david.brown@hesbynett.no> - 2017-01-20 18:01 +0100
              Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 09:26 -0800
                Re: while loop condition doesn't work David Brown <david.brown@hesbynett.no> - 2017-01-20 19:02 +0100
                Re: while loop condition doesn't work Alla _ <modelling.data@gmail.com> - 2017-01-20 10:13 -0800
                Re: while loop condition doesn't work Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-21 05:36 -0800

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