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Re: A Note on Readability

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From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: A Note on Readability
Date Mon, 13 Jul 2015 13:46:08 -0700
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James Kuyper <jameskuyper@verizon.net> writes:
[...]
> During translation phase 3, "3until" must be parsed as a preprocessing
> number ('3') followed by an identifier - keywords are not relevant until
> phase 7. During translation phase 7, "Each preprocessing token is
> converted into a token." - there's no merging and no splitting.
[...]

The syntax for a "preprocessing number" is a bit odd.  Obviously
"3until" isn't a number, but it is a preprocessing number.  So is
".xyze+" -- but not ".xyzf+".  "0x123" is a valid preprocessing number
-- and so is "0y123".

The reason, as far as I can tell, is to make the preprocessor's job
simpler.  The syntax of a preprocessing number covers the syntax of all
integer and floating-point numeric constants, with or without decimal
points, base prefixes, exponents, and suffixes.  It's designed to be
reasonably simple (you can see the grammar in N1570 6.4.8), and as a
result it covers a lot of things that aren't syntactically valid in
later phases; a grammar covering only *valid* numeric constants would be
more complicated.  Translation phase 7 (more or less the compiler
excluding the preprocessor) is responsible for converting preprocessing
numbers to numeric constants, and diagnosing any that are invalid.

-- 
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"

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Thread

A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-06 18:54 -0700
  A Note on Readability asetofsymbols@gmail.com - 2015-05-06 23:08 -0700
    Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-07 07:34 +0100
      Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-07 12:22 -0700
        Re: A Note on Readability raltbos@xs4all.nl (Richard Bos) - 2015-05-17 10:50 +0000
          Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-17 09:40 -0700
            Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-17 18:06 +0100
              Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 10:38 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 14:07 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-19 10:07 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-19 11:23 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-20 08:41 -0700
                Re: A Note on Readability asetofsymbols@gmail.com - 2015-05-20 09:03 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:09 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:08 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-20 17:15 +0100
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:10 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 08:58 -0700
                Re: A Note on Readability glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-21 17:33 +0000
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:47 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:08 -0500
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-20 13:43 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 10:59 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 18:05 -0500
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 17:36 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 22:12 -0500
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-20 20:34 -0700
                Re: A Note on Readability glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-21 04:39 +0000
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-21 17:41 -0700
                Re: A Note on Readability gwowen <gwowen@gmail.com> - 2015-05-21 01:14 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:26 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-21 10:33 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:42 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:53 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-23 10:01 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-23 14:53 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:18 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:13 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 09:38 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 12:40 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:56 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:35 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 10:08 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 11:07 -0700
                Re: A Note on Readability Robert Wessel <robertwessel2@yahoo.com> - 2015-05-27 20:17 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 09:56 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 09:58 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-26 18:16 +0100
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:55 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:01 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 09:58 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-27 18:11 +0100
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-28 12:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-28 12:55 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-29 10:08 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-06-01 18:54 +0100
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-10 11:29 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-11 09:06 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 13:42 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-12 09:20 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-12 11:24 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-13 08:48 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 12:38 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-13 10:34 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 14:43 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 12:18 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 15:27 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 08:45 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-14 09:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 09:41 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-14 10:26 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-15 19:59 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-14 12:25 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 13:46 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 08:33 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 11:17 -0700
                Re: A Note on Readability Richard Damon <Richard@Damon-Family.org> - 2015-07-13 21:06 -0400
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 22:38 -0400
                Re: A Note on Readability Richard Damon <Richard@Damon-Family.org> - 2015-07-15 08:19 -0400
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-20 09:10 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 11:00 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-15 08:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 10:57 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:51 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:36 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 10:00 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:05 -0700
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-24 16:43 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:57 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:37 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 10:14 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:11 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:26 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-26 18:38 +0100
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:24 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 10:06 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 11:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:38 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-24 07:01 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:58 -0700
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-25 00:45 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-10 11:09 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:04 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-21 10:36 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:56 -0700
                Re: A Note on Readability Robert Wessel <robertwessel2@yahoo.com> - 2015-05-22 12:16 -0500
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-22 14:14 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-23 09:49 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:55 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:58 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 10:26 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-18 11:08 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-19 10:09 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 20:40 +0100
            Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-17 14:34 -0400
              Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 10:40 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-18 11:18 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 14:33 -0400
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 20:44 +0100
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 16:07 -0400

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