From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
Subject: [TUHS] // comment in C++
Date: Thu, 9 Feb 2017 09:44:15 -0500 (EST) [thread overview]
Message-ID: <20170209144415.65AB418C11C@mercury.lcs.mit.edu> (raw)
> From: Michael Kjorling
> That wouldn't have anything to do with how ^@ is a somewhat common
> representation of 000, would it? .. I've always kind of wondered where
> that notation came from.
Well, CTRL-<*> is usually just the <*> character with the high bits cleared.
So, to have a printing representation of NULL, you have two character choices
- SPACE, and '@'. Printing "^ " is not so hot, so "^@" is better.
Also, if you look at an ASCII table, usually people just take the @-_ column,
and use that, since every character in that column has a printing
representation. The ' '-? column is missing the ' ', and `-<DEL> is missing
the DEL. So if you just take a CTRL character and set the 0100 bit, and print
it as "^<char>", you get something readable.
(Note that CTRL-' ' _is_ usually used when one needs to _input_ a NUL
character.)
Noel
next reply other threads:[~2017-02-09 14:44 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-09 14:44 Noel Chiappa [this message]
2017-02-09 16:51 ` Steffen Nurpmeso
2017-02-09 19:36 ` Steffen Nurpmeso
-- strict thread matches above, loose matches on Subject: below --
2017-02-09 21:14 Doug McIlroy
2017-02-10 17:39 ` Steffen Nurpmeso
[not found] <mailman.204.1486594285.3779.tuhs@minnie.tuhs.org>
2017-02-09 0:03 ` Paul McJones
2017-02-09 2:28 ` Marc Rochkind
2017-02-09 13:11 ` Tony Finch
2017-02-08 18:06 ron minnich
2017-02-08 18:08 ` A. P. Garcia
2017-02-08 18:17 ` arnold
2017-02-08 23:39 ` Steve Johnson
2017-02-08 23:52 ` Dave Horsfall
2017-02-09 2:11 ` Corey Lindsly
2017-02-09 2:46 ` Dave Horsfall
2017-02-09 2:53 ` Corey Lindsly
2017-02-09 4:38 ` Warner Losh
2017-02-09 2:47 ` Steve Nickolas
2017-02-09 4:55 ` Steve Johnson
2017-02-09 11:59 ` Michael Kjörling
2017-02-09 21:56 ` Dave Horsfall
2017-02-10 0:17 ` Dan Cross
2017-02-10 1:58 ` Dave Horsfall
2017-02-10 2:46 ` Nemo
2017-02-10 2:49 ` Dave Horsfall
2017-02-10 9:30 ` arnold
2017-02-10 9:19 ` arnold
2017-02-09 12:18 ` Brantley Coile
2017-02-09 13:31 ` Nick Downing
2017-02-08 22:45 ` Greg 'groggy' Lehey
2017-02-08 22:50 ` Ron Natalie
2017-02-08 23:22 ` Greg 'groggy' Lehey
2017-02-09 12:12 ` Michael Kjörling
2017-02-09 12:26 ` Lars Brinkhoff
2017-02-09 14:37 ` Random832
2017-02-09 14:49 ` Random832
2017-02-09 12:31 ` Paul Ruizendaal
2017-02-09 13:07 ` Steffen Nurpmeso
2017-02-08 22:51 ` ron minnich
2017-02-08 23:22 ` Greg 'groggy' Lehey
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