Re: utf-8 & ncurses

[Thomas Dickey]

On Tue, 17 Aug 2010, folkert wrote:

> Hi,
>
> I'm trying to get ncurses and utf-8 to work with each other.
> Let's say I have a string 'string' and an index 'loop'. Now in this
> string some utf-8 characters may exist. I try to filter these out and
> print them.
>
> #include <ncursesw/ncurses.h>
>
>         if ((string[loop] & 0xe0) == 0xc0)
>         {
>                 wadd_wch(win -> win, (string[loop] << 8) + string[loop + 1]);
>                 loop += 1;
>         }
>         else if ((string[loop] & 0xf0) == 0xe0)
>         {
>                 wadd_wch(win -> win, (string[loop] << 16) + (string[loop + 1] 
> << 8) + string[loop + 2]);
>                 loop += 2;
>         }
> ....
>
> This doesn't work. No special characters are shown.

The conversion doesn't look right.  Basically, UTF-8 uses a few bits from
each byte to tell where it is in a multibyte sequence, and a few bits from
each byte are masked into the result.

ncurses (assuming the locale is set via setlocale...) accepts the bytes
of a UTF-8 string in waddch (unlike X/Open, which requires using wadd_wch,
etc).

To do the conversion, ncurses uses functions such as mbrtowc().

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net