Xref: news2.mv.net comp.lang.c:56548 comp.lang.c++:72617 comp.os.msdos.djgpp:1127 gnu.g++.help:4636 gnu.gcc.help:5828
From: rfg AT monkeys DOT com (Ronald F. Guilmette)
Newsgroups: comp.lang.c,comp.lang.c++,gnu.gcc.help,gnu.g++.help,comp.os.msdos.djgpp
Subject: Re: float != float and floats as return types
Date: 15 Feb 1996 01:23:58 -0800
Organization: Infinite Monkeys & Co.
Lines: 33
Message-ID: <4fuu3e$6c9@segfault.monkeys.com>
References: <4ej9lb$mpc AT fu-berlin DOT de> <4eqc7l$ugh AT godzilla DOT zeta DOT org DOT au> <4eqtu3$ddo AT der DOT twinsun DOT com> <TANMOY DOT 96Feb1164022 AT qcd DOT lanl DOT gov>
NNTP-Posting-Host: segfault.monkeys.com
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

In article <TANMOY DOT 96Feb1164022 AT qcd DOT lanl DOT gov>,
Tanmoy Bhattacharya <tanmoy AT qcd DOT lanl DOT gov> wrote:
>In article <4eqtu3$ddo AT der DOT twinsun DOT com> eggert AT twinsun DOT com (Paul
>Eggert) writes: 
><snip>
>   bde AT zeta DOT org DOT au (Bruce Evans) writes:
>
>   >    a = 1.0;
>   >    b = FLT_EPSILON / 4.0;
>   >    c = a + b;
>   >    assert(c == (float) (a + b));
>
>   As far as I can tell the C Standard allows the assertion to either
>   succeed or fail, depending on the implementation.  The key phrase in
>   the standard is ``The values of floating operands and of the results of
>   floating expressions may be represented in greater precision and range
>   than that required by the type''.  So `c' might be represented in more
>   bits than `(float) (a + b)' (or vice versa! though this is more
>   controversial since it contradicts the Rationale, and it may be
>   corrected by the committee soon), and the assertion might fail.
>
>I do not agree with this interpretation, as the footnote (technically,
>not part of the standard) clarifies: an assignment and cast both must
>truncate the result to the required precision...

As must the act of returning a result from a function... according to the
official response to one Defect Report which was filed against the standard.

-- 

-- Ron Guilmette, Roseville, CA -------- Infinite Monkeys & Co. ------------
---- E-mail: rfg AT monkeys DOT com ----------- Purveyors of Compiler Test Suites -
------ Copyright (c) 1996 by Ronald F. Guilmette; All rights reserved. -----