On Wed, Dec 4, 2013 at 9:29 AM, Eli Zaretskii <
eliz@gnu.org> wrote:
> > From: Josh <
josh@foxtail.org>
> > Date: Wed, 4 Dec 2013 06:00:46 -0800
> > Cc: Michael Albinus <
michael.albinus@gmx.de>,
16048@debbugs.gnu.org> > On Wed, Dec 4, 2013 at 5:07 AM, Andreas Schwab <
schwab@linux-m68k.org>wrote:
> > >
michael.albinus@gmx.de writes:
> > >
> > > > The following form evals to nil:
> > > >
> > > > (string-equal "\377" "ÿ")
> > >
> > > "\377" is a unibyte string. When converted to multibyte it yields
> > > "\x3fffff".
> >
> >
> > At least as of 24.3, the manual[0] suggests that such a conversion
> > should not occur in this case:
> And it doesn't occur, indeed:
>
> (multibyte-string-p "\377")
>
> => nil
>
> > You can also use hexadecimal escape sequences (`\xN') and octal
> > escape sequences (`\N') in string constants. *But beware:* If a
> > string constant contains hexadecimal or octal escape sequences,
> > and these escape sequences all specify unibyte characters (i.e.,
> > less than 256), and there are no other literal non-ASCII
> > characters or Unicode-style escape sequences in the string, then
> > Emacs automatically assumes that it is a unibyte string. That is
> > to say, it assumes that all non-ASCII characters occurring in the
> > string are 8-bit raw bytes.
> >
> > [0] (info "(elisp) Non-ASCII in Strings")
> Best citation contest? you're on!
No, thanks. I haven't entered such contests in many years.
> -- Function: string= string1 string2
> This function returns `t' if the characters of the two strings
> match exactly. Symbols are also allowed as arguments, in which
> case the symbol names are used. Case is always significant,
> regardless of `case-fold-search'.
>
> [...]
>
> For technical reasons, a unibyte and a multibyte string are
> `equal' if and only if they contain the same sequence of character
> codes and all these codes are either in the range 0 through 127
> (ASCII) or 160 through 255 (`eight-bit-graphic'). However, when a
> unibyte string is converted to a multibyte string, all characters
> with codes in the range 160 through 255 are converted to
> characters with higher codes, whereas ASCII characters remain
> unchanged. Thus, a unibyte string and its conversion to multibyte
> are only `equal' if the string is all ASCII.
>
> Note the last sentence.
Yes, I must have misunderstood Andreas' meaning; I believed he was
suggesting that the two strings compared differently due to "\377"
having been converted to a multibyte string and therefore miscomparing
with the unibyte (or so I thought) string "ÿ". I see now that I had
it exactly backwards. Thanks for setting me straight.