GNU bug report logs - #6283
doc/lispref/searching.texi reference to octal code `0377' correct?

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Message #41 received at 6283 <at> debbugs.gnu.org (full text, mbox):

From: MON KEY <monkey <at> sandpframing.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 6283 <at> debbugs.gnu.org
Subject: Re: bug#6283: doc/lispref/searching.texi reference to octal code 
	`0377' correct?
Date: Mon, 31 May 2010 20:24:00 -0400

On Mon, May 31, 2010 at 2:49 PM, Eli Zaretskii <eliz <at> gnu.org> wrote:
>> > In Unicode, it's a codepoint of LATIN SMALL LETTER Y WITH DIAERESIS.
>>
>> I don't understand this.
>
> I don't know how to express this more clearly.  Perhaps you could ask
> specific questions.
>

If you step through the Emacs Lisp example I sent along previously you
may notice that the search doesn't match either of the `ÿ's.

It does however match the character with numeric notations:

 4194303, #o17777777, #x3fffff
 4194221, #o17777655, #x3fffad

E.g. These rawbytes as presented by Emacs as characters:

 (insert-byte (multibyte-char-to-unibyte 4194221) 1)
 (insert-byte (multibyte-char-to-unibyte 4194303) 1)

This is what I don't understand.

If I evauate the following:

 (progn
   (save-excursion
     (insert-byte (multibyte-char-to-unibyte 4194221) 1)
     (insert-byte (multibyte-char-to-unibyte 4194303) 1))
   (search-forward-regexp "ÿ" nil t))

I don't match.

Whereas if I evaluate:

 (progn
   (save-excursion (insert 10 #o377))
   (search-forward-regexp "ÿ" nil t))

I get a match.

Likewise, if I evaluate

 (progn (save-excursion (insert 10 4194303))
        (search-forward-regexp "\377" nil t))

I get a match.

Which is to say, given the example regexp from the manual, i.e:

,----
| You cannot always match all non-ASCII characters with the regular
| expression `"[\200-\377]"'
`----

I am unable to locate the character: ÿ (255, #o377, #xff) e.g.
LATIN SMALL LETTER Y WITH DIAERESIS

To be clear, my issue isn't that I am not able to match `ÿ' but rather
that I am able to match the raw-byte character representation with a
visual appearance which coincides with the octal value for the `ÿ'
character code i.e. #o377 this being otherwise widely understood as
`octal 0377'.

I hope this is more clear than the previous mail. I apologize if it is not.

--
/s_P]

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