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Groups > comp.lang.c > #17243

Re: Is this broken or wot?

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: Is this broken or wot?
Date 2012-02-13 12:59 -0800
Organization None to speak of
Message-ID <lnsjieih4v.fsf@nuthaus.mib.org> (permalink)
References <jhbm7t$9ng$1@speranza.aioe.org>

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Robert Samelson <robs@invalid.com> writes:
> unsigned x = 0;
> if(x-- < 4)
>                 printf("foo\n");
> else
>                 printf("bar\n");
>
> GCC for Data General Aviion 5000 (an 88000 machine) will convert this 
> into:
>
>         unsigned x = 0;
>         if(--x < 3) ....
>
> in the assembly.
>
> This seems broken if x == ~0.

It's broken if and only if the program produces incorrect output.  C
code specifies behavior, not machine code.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Thread

Is this broken or wot? Robert Samelson <robs@invalid.com> - 2012-02-13 18:53 +0000
  Re: Is this broken or wot? Willem <willem@toad.stack.nl> - 2012-02-13 19:19 +0000
  Re: Is this broken or wot? Barry Schwarz <schwarzb@dqel.com> - 2012-02-13 12:14 -0800
    Re: Is this broken or wot? James Kuyper <jameskuyper@verizon.net> - 2012-02-13 15:40 -0500
  Re: Is this broken or wot? Keith Thompson <kst-u@mib.org> - 2012-02-13 12:59 -0800
  Re: Is this broken or wot? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-13 14:30 -0800
    Re: Is this broken or wot? "Bl0ckeduser ." <bl0ckedusersoft@gmail.com> - 2012-02-13 18:13 -0800

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