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Re: Program to cipher a text, new thread, fresh one

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: Program to cipher a text, new thread, fresh one
Date 2015-10-31 20:32 +0000
Organization A noiseless patient Spider
Message-ID <874mh6aiew.fsf@bsb.me.uk> (permalink)
References (1 earlier) <1e1a0897-ba67-47b3-b778-0bc03f8b098b@googlegroups.com> <87oaffb4z9.fsf@bsb.me.uk> <n12oak$mom$1@dont-email.me> <8737wraqhw.fsf@bsb.me.uk> <n130a5$ob3$1@dont-email.me>

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Bartc <bc@freeuk.com> writes:

> On 31/10/2015 17:37, Ben Bacarisse wrote:
>> Bartc <bc@freeuk.com> writes:
>>
>>> On 31/10/2015 12:24, Ben Bacarisse wrote:
>
>>> I tried to make it do the same encoding as yours, but there is a
>>> difference which might be a bug in your code, or a lack of
>>> understanding on my part: lower case strings are encoded differently
>>> from the same upper case input.
>>>
>>> So with key "ABC", then your program encodes "AAA" to "ABC", but "aaa"
>>> to "acb" (after restarting). (I assume that key "AAA..." having no
>>> effect is intentional.)
>>
>> That would be a bug, but I can't reproduce it.  I've checked with the
>> code I posted (in case I posted something other that the last version),
>> and it seems to work as expected:
>
> OK, it's to do with the isalpha() function; some libraries in Windows
> return 1 or 2 for an alpha character (for upper or lower case
> presumably), and you use that to step along the key string.

Good spot.  That should have been !!isalpha() (or similar).  Thanks.

<snip>
>>> Anyway, in mine other differences are:
>>>
>>> * Requires ASCII (this is checked for)
>>
>> It's not entirely clear what ASCII means.  You assume some things about
>> the letters (they they are contiguous) and you assume that no char
>> values are negative.  Is that what you mean?  Some encodings that some
>> people would call ASCII have negative characters.
>
> ASCII codes go up to 127. But the values of interest are 65 to 90, and
> 97 to 122, which are always going to be positive.
>
>>> * Is line-based, with lines limited to 500 characters.
>>
>> Why?  It seems to complicate the program.
>
> To give an idea of what it looks like.

Fair enough.

> A bit more complicated, but far
> more flexible. So I can grab an input string (from the console, file,
> data in a program or just construct it), and then do whatever I want
> with it including encoding or decoding, or reverse the string first
> and then encode.
>
> That's a lot harder if the input is trickled in a character at a time.

That depends on your computing environment.  In mine I can do what you
describe using my version.  But I can't easily use your version in a
pipeline, for example.  I'd say that wit the right execution environment
(i.e. a good shell), a plain filter like mine is the more flexible.

>>> (Yours also
>>> seemed to be line based, in that after pressing Enter, you got the
>>> encoded string, then it waited for another line, but that was an
>>> illusion. Strange though because after entering what you thought was
>>> the same line of input, you got a different encoding!
>>
>> I don't know what this means but my program is not line-oriented at all.
>> It sounds like you had some trouble running it.  It's the simplest form
>> of filter, if that helps you work out how to test it.
>
> I ran it on Windows and Linux and they were the same (apart from the
> isalpha thing). Transcribed manually:
>
> ...$ ./a.out ABC
> LINE1
> LJPE1
> LINE2
> MKNF2
> LINE3
> NIOG3
> ^Z
> ... Stopped
>
> The input was LINE1 Enter, LINE2 Enter, LINE3 Enter. The characters
> are shown as I type, then as I press Enter, the encoded line is
> displayed, then it sits waiting for more input.
>
> It does look remarkably like it's reading a line at a time, outputting
> the encoding, then waiting for the next. Except the keystring is not
> reset and that gives confusing results.

Yes, the key string is not reset.  That's because it's not line
oriented.  And it seems odd that don't know that your shell's input is
line buffered (you can turn that off if you like).  That does not mean
the program is line-oriented.

-- 
Ben.

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Thread

Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 08:23 -0700
  Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-10-30 15:39 +0000
    Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 09:33 -0700
    Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-01 09:33 +0000
  Re: Program to cipher a text, new thread, fresh one Mark Storkamp <mstorkamp@yahoo.com> - 2015-10-30 11:17 -0500
    Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 09:32 -0700
      Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-01 09:38 +0000
  Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-10-30 10:55 -0600
    Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-01 10:07 +0000
      Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-01 10:42 +0000
        Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-01 11:35 +0000
          Re: Program to cipher a text, new thread, fresh one James Kuyper <jameskuyper@verizon.net> - 2015-11-01 08:33 -0500
          Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-01 16:09 +0000
            Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-11-02 12:43 +0000
              Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-02 13:25 +0000
              Re: Program to cipher a text, new thread, fresh one Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-02 06:13 -0800
          Re: Program to cipher a text, new thread, fresh one Keith Thompson <kst-u@mib.org> - 2015-11-01 12:26 -0800
      Re: Program to cipher a text, new thread, fresh one supercat@casperkitty.com - 2015-11-01 07:59 -0800
        Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-02 13:48 +0000
          Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-11-02 14:06 +0000
            Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-02 14:51 +0000
              Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-11-02 15:48 +0000
                Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-02 16:00 +0000
                Re: Program to cipher a text, new thread, fresh one asetofsymbols@gmail.com - 2015-11-03 01:40 -0800
                Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 11:16 +0000
                Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-11-03 05:21 -0600
                Re: Program to cipher a text, new thread, fresh one asetofsymbols@gmail.com - 2015-11-03 03:41 -0800
                Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 11:53 +0000
                Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-11-03 05:57 -0600
                Re: Program to cipher a text, new thread, fresh one Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 12:48 +0000
                Re: Program to cipher a text, new thread, fresh one Rosario19 <Ros@invalid.invalid> - 2015-11-04 09:09 +0100
                Re: Program to cipher a text, new thread, fresh one Rosario19 <Ros@invalid.invalid> - 2015-11-04 09:37 +0100
                Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-11-04 07:09 -0800
                Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-11-03 05:53 -0600
                Re: Program to cipher a text, new thread, fresh one asetofsymbols@gmail.com - 2015-11-03 04:29 -0800
                Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-11-03 06:42 -0600
      Re: Program to cipher a text, new thread, fresh one Geoff <geoff@invalid.invalid> - 2015-11-01 08:07 -0800
      Re: Program to cipher a text, new thread, fresh one Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-02 02:26 -0800
        Re: Program to cipher a text, new thread, fresh one Rosario19 <Ros@invalid.invalid> - 2015-11-06 07:53 +0100
          Re: Program to cipher a text, new thread, fresh one Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-07 10:01 -0800
  Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 10:50 -0700
    Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 10:53 -0700
      Re: Program to cipher a text, new thread, fresh one Barry Schwarz <schwarzb@dqel.com> - 2015-10-30 11:52 -0700
        Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 12:12 -0700
          Re: Program to cipher a text, new thread, fresh one Barry Schwarz <schwarzb@dqel.com> - 2015-10-30 21:05 -0700
            Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 23:58 -0700
              Re: Program to cipher a text, new thread, fresh one Barry Schwarz <schwarzb@dqel.com> - 2015-10-31 03:09 -0700
                Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 03:47 -0700
                Re: Program to cipher a text, new thread, fresh one Barry Schwarz <schwarzb@dqel.com> - 2015-10-31 11:42 -0700
      Re: Program to cipher a text, new thread, fresh one Barry Schwarz <schwarzb@dqel.com> - 2015-10-30 12:04 -0700
      Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 12:10 -0700
  Re: Program to cipher a text, new thread, fresh one "Osmium" <r124c4u102@comcast.net> - 2015-10-30 13:17 -0600
    Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 00:04 -0700
      Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 00:25 -0700
  Re: Program to cipher a text, new thread, fresh one Keith Thompson <kst-u@mib.org> - 2015-10-30 12:34 -0700
    Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-30 21:49 -0700
      Re: Program to cipher a text, new thread, fresh one Keith Thompson <kst-u@mib.org> - 2015-10-31 13:18 -0700
  Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 00:29 -0700
  Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 01:12 -0700
    Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-31 12:24 +0000
      Re: Program to cipher a text, new thread, fresh one Alla _ <modelling.data@gmail.com> - 2015-10-31 06:11 -0700
      Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-10-31 15:58 +0000
        Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-31 17:37 +0000
          Re: Program to cipher a text, new thread, fresh one Bartc <bc@freeuk.com> - 2015-10-31 18:14 +0000
            Re: Program to cipher a text, new thread, fresh one Keith Thompson <kst-u@mib.org> - 2015-10-31 13:29 -0700
              Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-31 20:35 +0000
            Re: Program to cipher a text, new thread, fresh one Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-31 20:32 +0000
  Re: Program to cipher a text, new thread, fresh one Rosario19 <Ros@invalid.invalid> - 2015-11-04 09:50 +0100

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