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Re: A few questiosn about encoding

References <6dfa3707-80f4-407a-a109-66dbb0130513@googlegroups.com> <mailman.2923.1370797972.3114.python-list@python.org> <kp9drh$1o0t$1@news.ntua.gr> <mailman.3238.1371163584.3114.python-list@python.org> <kpea1c$p37$1@news.ntua.gr>
From Zero Piraeus <schesis@gmail.com>
Date 2013-06-14 02:00 -0400
Subject Re: A few questiosn about encoding
Newsgroups comp.lang.python
Message-ID <mailman.3253.1371189687.3114.python-list@python.org> (permalink)

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:

On 14 June 2013 01:34, Nick the Gr33k <support@superhost.gr> wrote:
> Why doesn't it work like this?
>
> leading 0 = 1 byte flag
> leading 1 = 2 bytes flag
> leading 00 = 3 bytes flag
> leading 01 = 4 bytes flag
> leading 10 = 5 bytes flag
> leading 11 = 6 bytes flag
>
> Wouldn't it be more logical?

Think about it. Let's say that, as per your scheme, a leading 0
indicates "1 byte" (as is indeed the case in UTF8). What things could
follow that leading 0? How does that impact your choice of a leading
00 or 01 for other numbers of bytes?

... okay, you're obviously going to need to be spoon-fed a little more
than that. Here's a byte:

  01010101

Is that a single byte representing a code point in the 0-127 range, or
the first of 4 bytes representing something else, in your proposed
scheme? How can you tell?

Now look at the way UTF8 does it:
<http://en.wikipedia.org/wiki/Utf-8#Description>

Really, follow the link and study the table carefully. Don't continue
reading this until you believe you understand the choices that the
designers of UTF8 made, and why they made them.

Pay particular attention to the possible values for byte 1. Do you
notice the difference between that scheme, and yours:

  0xxxxxxx
  1xxxxxxx
  00xxxxxx
  01xxxxxx
  10xxxxxx
  11xxxxxx

If you don't see it, keep looking until you do ... this email gives
you more than enough hints to work it out. Don't ask someone here to
explain it to you. If you want to become competent, you must use your
brain.

 -[]z.

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Thread

A few questiosn about encoding Νικόλαος Κούρας <nikos.gr33k@gmail.com> - 2013-06-09 03:44 -0700
  Re: A few questiosn about encoding Fábio Santos <fabiosantosart@gmail.com> - 2013-06-09 13:18 +0100
  Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-09 18:01 +0100
  Re: A few questiosn about encoding Chris “Kwpolska” Warrick <kwpolska@gmail.com> - 2013-06-09 19:12 +0200
    Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-12 09:09 +0000
      Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-12 09:24 +0000
        Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-12 14:23 +0300
          Re: A few questiosn about encoding Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-06-12 14:52 +0200
          Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-12 21:30 +0100
            Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 01:40 +0000
              Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 12:01 +1000
                Re: A few questiosn about encoding Nobody <nobody@nowhere.com> - 2013-06-13 11:02 +0100
            Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 09:21 +0300
              Re: A few questiosn about encoding jmfauth <wxjmfauth@gmail.com> - 2013-06-12 23:28 -0700
              Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 16:48 +1000
          Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 00:13 +0000
            Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 09:09 +0300
              Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 07:11 +0000
                Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 10:42 +0300
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 17:58 +1000
                Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 11:08 +0300
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-13 18:20 +1000
                Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 12:41 +0300
                Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 11:49 +0000
                Re: A few questiosn about encoding Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 17:19 +0300
                Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 11:00 +1000
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 09:59 +0300
                Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 20:14 +1000
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 16:58 +0300
                Re: A few questiosn about encoding Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-14 11:21 -0400
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 18:26 +0300
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:03 +1000
                Re: A few questiosn about encoding Walter Hurry <walterhurry@lavabit.com> - 2013-06-14 23:32 +0000
                Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-15 10:26 +1000
                Re: A few questiosn about encoding Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-15 06:34 +0000
                Re: A few questiosn about encoding Grant Edwards <invalid@invalid.invalid> - 2013-06-15 14:44 +0000
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 17:49 +0300
                Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-15 15:30 +0000
                Re: A few questiosn about encoding Roy Smith <roy@panix.com> - 2013-06-15 10:59 -0400
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 18:14 +0300
                Re: A few questiosn about encoding Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-15 11:35 -0400
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-15 22:26 +0300
                Re: A few questiosn about encoding Benjamin Schollnick <benjamin@schollnick.net> - 2013-06-15 16:35 -0400
                Re: A few questiosn about encoding Chris “Kwpolska” Warrick <kwpolska@gmail.com> - 2013-06-16 15:45 +0200
                Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 09:36 +0200
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 10:49 +0300
                Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 10:22 +0200
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 11:37 +0300
                Don't feed the troll... (was: Re: A few questiosn about encoding) Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 11:06 +0200
                Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:32 +0300
                Re: Don't feed the troll... Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 13:09 +0200
                Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:36 +0300
                Re: Don't feed the troll... Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-14 08:44 -0400
                Re: Don't feed the troll... Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 15:25 +0200
                Re: Don't feed the troll... Neil Cerutti <neilc@norwich.edu> - 2013-06-14 15:54 +0000
                Re: Don't feed the troll... Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 12:15 +0200
                Re: Don't feed the troll... Guy Scree <nobody@nowhere.com> - 2013-06-14 18:50 -0400
                Re: Don't feed the troll... Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-15 06:31 +0000
                Re: Don't feed the troll... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-15 13:04 -0400
                Re: Don't feed the troll... Guy Scree <nobody@nowhere.com> - 2013-06-17 16:15 -0400
                Re: Don't feed the troll... Chris Angelico <rosuav@gmail.com> - 2013-06-18 07:46 +1000
                Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-14 20:19 +1000
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:41 +0300
                Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 11:20 +0100
                Re: Don't feed the troll... (was: Re: A few questiosn about encoding) rusi <rustompmody@gmail.com> - 2013-06-14 04:51 -0700
                Re: Don't feed the help-vampire rusi <rustompmody@gmail.com> - 2013-06-14 05:09 -0700
                Re: Don't feed the help-vampire Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 14:31 +0200
                Re: Don't feed the help-vampire Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-14 10:51 -0600
                Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:50 +0300
                Re: Don't feed the troll... Zero Piraeus <schesis@gmail.com> - 2013-06-14 09:33 -0400
                Re: Don't feed the troll... Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:45 +0300
                Re: Don't feed the troll... Heiko Wundram <modelnine@modelnine.org> - 2013-06-14 14:58 +0200
                Re: Don't feed the troll... Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 14:25 +0100
                Re: Don't feed the troll... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-14 17:12 +0100
                Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 12:50 +0200
                Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 15:59 +0300
                Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 15:52 +0200
                Re: A few questiosn about encoding Cameron Simpson <cs@zip.com.au> - 2013-06-15 10:28 +1000
                Re: A few questiosn about encoding Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-17 08:49 +0200
                Re: Don't feed the troll... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-14 12:57 +0100
                Re: Don't feed the troll... (was: Re: A few questiosn about encoding) "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 13:13 -0400
                Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:31 +1000
                Re: Don't feed the troll... (was: Re: A few questiosn about encoding) Grant Edwards <invalid@invalid.invalid> - 2013-06-14 19:40 +0000
                Re: Don't feed the troll "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 13:56 -0400
                Re: Don't feed the troll Tim Chase <python.list@tim.thechases.com> - 2013-06-14 14:00 -0500
                Re: Don't feed the troll "D'Arcy J.M. Cain" <darcy@druid.net> - 2013-06-14 15:17 -0400
                Re: Don't feed the troll... Ben Finney <ben+python@benfinney.id.au> - 2013-06-15 10:42 +1000
                Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-19 18:46 -0700
                Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-20 06:26 +0000
                Re: A few questiosn about encoding MRAB <python@mrabarnett.plus.com> - 2013-06-20 12:43 +0100
                Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-20 09:27 -0700
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 02:37 +1000
                Re: A few questiosn about encoding MRAB <python@mrabarnett.plus.com> - 2013-06-20 18:17 +0100
                Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-23 08:51 -0700
                Re: A few questiosn about encoding Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 16:30 +0000
                Re: A few questiosn about encoding wxjmfauth@gmail.com - 2013-06-25 13:16 -0700
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 03:21 +1000
                Re: A few questiosn about encoding Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-20 20:43 +0100
                Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 06:40 -0700
                Re: A few questiosn about encoding Andrew Berg <robotsondrugs@gmail.com> - 2013-06-20 09:04 -0500
                Re: A few questiosn about encoding Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 08:12 -0700
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 01:26 +1000
                Re: A few questiosn about encoding Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-20 20:25 +0300
                Re: A few questiosn about encoding Chris Angelico <rosuav@gmail.com> - 2013-06-21 01:28 +1000
                Re: A few questiosn about encoding Andreas Perstinger <andipersti@gmail.com> - 2013-06-20 19:08 +0200
        Re: A few questiosn about encoding Dave Angel <davea@davea.name> - 2013-06-12 08:43 -0400
      Re: A few questiosn about encoding Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-13 18:46 -0400
        Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 08:34 +0300
          Re: A few questiosn about encoding Zero Piraeus <schesis@gmail.com> - 2013-06-14 02:00 -0400
            Re: A few questiosn about encoding Nick the Gr33k <support@superhost.gr> - 2013-06-14 10:28 +0300

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