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From: steffen@sdaoden.eu (Steffen Nurpmeso)
Subject: [TUHS] // comment in C++
Date: Thu, 09 Feb 2017 17:51:31 +0100	[thread overview]
Message-ID: <20170209165131.r156l%steffen@sdaoden.eu> (raw)
In-Reply-To: <20170209144415.65AB418C11C@mercury.lcs.mit.edu>

jnc at mercury.lcs.mit.edu (Noel Chiappa) wrote:
 |> 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.

You xor it via toupper(X)^0x40, yes of course.  My code is right,
it is just the manual that is incomplete or even false: i will
clarify it.  It is just that i know that many people which use
free software don't know what a xor operation is, at least without
looking into Wikipedia.  (And even though i use it frequently
myself, that is often contaminated by politics, just yesterday
i had a hard time with some paragraphs on the German Wikipedia
page on intellectual properties.)

 |(Note that CTRL-' ' _is_ usually used when one needs to _input_ a NUL
 |character.)
 |
 | Noel

--steffen


  reply	other threads:[~2017-02-09 16:51 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-09 14:44 Noel Chiappa
2017-02-09 16:51 ` Steffen Nurpmeso [this message]
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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