Re: .5 against 0.5f

From	cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups	comp.lang.c
Subject	Re: .5 against 0.5f
Date	2026-10-30 01:17 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<11c0r7j$89a$1@reader2.panix.com> (permalink)
References	<11bpvs7$1e6kc$2@dont-email.me> <11bv4jd$37ch9$1@dont-email.me> <11bvsj4$3g32k$1@dont-email.me> <86o6cckttt.fsf@linuxsc.com>

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In article <86o6cckttt.fsf@linuxsc.com>,
Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>"Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> writes:
>> On Thu, 29 Oct 2026 10:45:16 +0100, David Brown wrote:
>>
>>> Let me put it another way.  What benefit do you think there is from
>>> these parentheses?  Why does the FreeBSD style guide recommend them?
>>> I can see benefits in consistency of style once that usage has been
>>> established, but why have them in the first place?
>>
>> As we all know, FreeBSD is derived from software developed by
>> the CSRG at UC Berkeley during the 70's.  FreeBSD adopted the
>> Kernel Normal Format (KNF) from CSRG.  You will need to contact
>> a former member of CSRG such as Bostik, McKusick, Joy, Leffler,
>> etc.  and them why KNF requires ().
>>
>> Perhaps, the C compiler from 40 or so years ago required
>> parentheses in a return statement.  Or, just maybe, members of
>> CSRG read K&R and noticed the authors of the book consistently
>> use paretheses in their examples.  Ah yes, let's look at
>> the documentation:
>>
>> % man 9 style
>>
>> HISTORY
>>     This manual page was originally based on the src/admin/style/style
>>     file from the 4.4BSD-Lite2 release, with frequent updates to
>>     reflect the current practice and desire of the FreeBSD project.
>>     src/admin/style/style is a codification by the CSRG of the
>>     programming style of Ken Thompson and Dennis Ritchie in Version6
>>     AT&T UNIX.
>>
>> So, it seems to be a preference of Ritchie.
>
>It may have been simply long-standing habit rather than preference.
>In the early days of C parentheses around return expressions were
>required, not optional.  I've been programming in C long enough to
>have been influenced by that requirement (and later learned to undo
>it).

When?  They were not required in typesetter C on 7th Edition
Unix, which is more or less what K&R described, and the grammar
in K&R1 just says `return _expression_;`:

```
$ ed paren.c
?paren.c
a
#include <stdio.h>

int
foo()
{
        return 2;
}

int
main()
{
        printf("foo() = %d\n", foo());
        return 0;
}
.
w
104
q
$ cc -o paren paren.c
$ ./paren
foo() = 2
$
```

Nor were they required in the rather different dialect used in
6th Edition Unix:

```
RESTRICTED RIGHTS

Use, duplication or disclosure is subject to
restrictions stated in Contract with Western
Electric Company, Inc.

login: root
# cat >paren.c
foo()
{
        return 2;
}

int
main()
{
        printf("foo() = %d\n", foo());
        return 0;
}
# cc paren.c
# ./a.out
foo() = 2
#
```

Neither the parser in the 5th Edition compiler nor the 4th Ed
compiler (the latter from the recently recovered tape found at
Utah) requires parentheses in that position, either.

They _are_ required in the earliest extant compiler sources from
roughly 1972 (the `last1120c` and `prestruct-c` compilers
recovered from DECtape and published by Dennis Ritchie on his
web page), and it is true that the, "C Reference Manual" from
6th Ed shows parentheses around the expression in a `return`
statement; as mentioned, the 6th Ed compiler did not enforce
this, however.

It looks like parentheses were grammatically required around the
expression in a `return` statement for a brief period ca. 1972,
perhaps into early 1973, and never after that.  Certainly, I do
not believe that anyone posting here ever used one of the early
compilers that required this, unless it was an ersatz
implementation.

	- Dan C.

Thread

.5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-27 11:53 +0100
  Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-27 17:45 +0000
    Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-27 18:50 +0100
      Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-27 19:01 +0000
        Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-27 20:15 +0100
          Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-27 19:54 +0000
            Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-27 13:10 -0700
              Re: .5 against 0.5f steve g <Sgonedes1977@gmail.com> - 2026-10-28 02:20 -0400
            Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-27 21:35 +0100
            Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-27 18:00 -0400
              Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-27 22:15 +0000
              Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-28 06:54 -0700
          Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-27 21:57 +0100
            Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-27 14:18 -0700
          Re: .5 against 0.5f steve g <Sgonedes1977@gmail.com> - 2026-10-28 02:19 -0400
            Re: .5 against 0.5f Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-28 21:54 +0000
              Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-28 14:58 -0700
      Re: .5 against 0.5f steve g <Sgonedes1977@gmail.com> - 2026-10-28 02:11 -0400
        Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-27 23:21 -0700
    Re: .5 against 0.5f scott@slp53.sl.home (Scott Lurndal) - 2026-10-27 18:40 +0000
      Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-27 12:29 -0700
        Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-27 13:11 -0700
          Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-27 13:25 -0700
      Re: .5 against 0.5f Michael S <already5chosen@yahoo.com> - 2026-10-27 21:43 +0200
        Re: .5 against 0.5f Michael S <already5chosen@yahoo.com> - 2026-10-27 22:05 +0200
          Re: .5 against 0.5f Michael S <already5chosen@yahoo.com> - 2026-10-27 22:51 +0200
      Re: .5 against 0.5f Kaz Kylheku <046-301-5902@kylheku.com> - 2026-10-27 20:05 +0000
        Re: .5 against 0.5f bartc <bc@freeuk.com> - 2026-10-27 21:03 +0000
        Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-27 15:41 -0700
          Re: .5 against 0.5f scott@slp53.sl.home (Scott Lurndal) - 2026-10-28 16:23 +0000
      Re: .5 against 0.5f steve g <Sgonedes1977@gmail.com> - 2026-10-28 02:25 -0400
      Re: .5 against 0.5f makendo <makendo@makendo.invalid> - 2026-10-29 18:04 +0800
        Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 05:01 -0700
          Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 13:55 +0100
            Re: .5 against 0.5f bartc <bc@freeuk.com> - 2026-10-29 14:32 +0000
          Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 23:19 +0100
        Re: .5 against 0.5f Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-30 00:50 +0000
    Re: .5 against 0.5f Kaz Kylheku <046-301-5902@kylheku.com> - 2026-10-27 19:58 +0000
    Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-27 17:43 -0400
      Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-27 18:06 -0400
        Re: .5 against 0.5f Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-28 00:49 +0000
          Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-27 18:23 -0700
            Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-28 16:38 +0100
              Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 13:27 -0700
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 00:08 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 16:56 -0700
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 18:55 +0100
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 09:30 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 04:54 -0700
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 19:57 +0100
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 20:56 +0100
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 23:06 +0100
                Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-29 13:39 -0700
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 16:56 -0700
          Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-27 21:41 -0400
            Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-28 08:45 +0100
          Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-28 01:50 +0000
            Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-28 07:32 +0100
              Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-28 07:51 +0100
                Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-28 07:55 +0100
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-28 16:27 +0000
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-28 17:44 +0100
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-28 16:22 +0000
                Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-28 19:15 +0100
                Re: .5 against 0.5f fir <profesor.fir@gmail.com> - 2026-10-28 19:47 +0100
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-28 19:10 +0000
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 13:31 -0700
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-28 22:44 +0000
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 00:27 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 16:39 -0700
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-29 00:22 +0000
                Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-28 17:59 -0700
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-29 01:50 +0000
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 10:45 +0100
                Re: .5 against 0.5f cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-29 14:56 +0000
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-29 16:34 +0000
                Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-29 15:47 -0700
                Re: .5 against 0.5f cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-30 01:17 +0000
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 16:46 -0700
                Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-29 11:56 -0400
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-29 17:57 +0000
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 16:06 -0700
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-30 00:21 +0000
                Re: .5 against 0.5f cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-29 19:49 +0000
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 22:55 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 16:29 -0700
                Re: .5 against 0.5f Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-29 23:46 +0000
                Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-29 18:37 -0700
                Re: .5 against 0.5f Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-29 17:58 +0100
                Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-29 15:42 -0700
                Re: .5 against 0.5f cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-30 01:27 +0000
                Re: .5 against 0.5f "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2026-10-30 02:08 +0000
          Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-28 08:39 +0100
            Re: .5 against 0.5f Michael S <already5chosen@yahoo.com> - 2026-10-28 22:25 +0200
              Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 10:48 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-29 04:59 -0700
            Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 14:26 -0700
              Re: .5 against 0.5f Michael S <already5chosen@yahoo.com> - 2026-10-29 00:12 +0200
                Re: .5 against 0.5f bartc <bc@freeuk.com> - 2026-10-28 22:33 +0000
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 11:01 +0100
                Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-28 16:05 -0700
                Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 10:59 +0100
            Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-28 14:34 -0700
              Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-29 11:06 +0100
          Re: .5 against 0.5f tTh <tth@none.invalid> - 2026-10-28 15:08 +0100
            Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-28 07:49 -0700
          Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-28 14:36 -0700
      Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-27 15:53 -0700
        Re: .5 against 0.5f James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-27 21:55 -0400
          Re: .5 against 0.5f Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-27 19:02 -0700
        Re: .5 against 0.5f David Brown <david.brown@hesbynett.no> - 2026-10-28 08:56 +0100
      Re: .5 against 0.5f Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-28 08:01 -0700
  Re: .5 against 0.5f "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-27 13:08 -0700

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