collate

[Dag Henriksson]

I'm trying to compare strings written in Swedish using:

std::locale loc(""); // System locale is Swedish
loc(first, second);

But this does not give me the right return value.
for example,

loc(string("å") , string("ä"));

should yield true, since 'å' is less than 'ä' in Swedish, but it doesn't.

Is this a bug?

--
Dag Henriksson

[Bo Persson]

Re: collate


"Dag Henriksson" <dag.henriksson @quidsoft.se> skrev i meddelandet
news:%239vshxuV DHA.2100@TK2MSF TNGP11.phx.gbl. ..[color=blue][color=green][color=darkred]
> > > I'm trying to compare strings written in Swedish using:
> > >
> > > std::locale loc(""); // System locale is Swedish
> > > loc(first, second);
> > >
> > > But this does not give me the right return value.
> > > for example,
> > >
> > > loc(string("å") , string("ä"));
> > >
> > > should yield true, since 'å' is less than 'ä' in Swedish, but it[/color]
> > doesn't.[color=darkred]
> > >
> > > Is this a bug?[/color]
> >
> > Well, not really, it just doesn't work.
> >
> > The C++ standard doesn't say much what happens for letters outside[/color][/color]
of[color=blue][color=green]
> > a-z. In Windows their positions even varies between different
> > character sets (try looking at them with the program
> > "Teckenuppsättn ing"). Most often 'ä' comes before 'å' (in an area
> > filled with varying sets of other accented glyphs that are not
> > "proper" letters).[/color]
>
> Yes, I know that the C++ standard does not put any requirements on[/color]
any[color=blue]
> other facets than "C", but if an implementation can create a locale
> named for example "Sweden_Swedish ", shouldn't the collate facet in[/color]
that[color=blue]
> locale then follow the rules of Swedish, or are you saying that this[/color]
is[color=blue]
> impossible in Windows because the AscII of a letter depends of the
> character set? Most lists I've seen of supported locales say what
> charmap is used for each locale, for example ISO-8859-1 for Swedish,[/color]
so[color=blue]
> this should not be a problem.[/color]

Ok, I change my statement to "it might work". I see that in the latest
library collate<char> indirectly calls the undocumented function
_Strcoll. Don't know what that means though.

If you say that it still doesn't work, I'm not the least surprised.


Bo Persson
bop2@telia.com

[color=blue]
>
> All book I have read suggests that it should be possible to compare
> strings according to local rules using collate. See for example
> http://www.research.att.com/~bs/3rd_loc.pdf
> where Stroustrup writes:
> "given the dk locale, we can construct a locale that reads and[/color]
compares[color=blue]
> strings according to the rules of Danish (that give three extra[/color]
vowels[color=blue]
> compared to English)"
>
> But maybe I've misunderstood something...
>
> --
> Dag Henriksson
>
>[/color]