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NAME | SYNOPSIS | DESCRIPTION | EXTENSIONS | NOTES | RETURN VALUE | PORTABILITY | SEE ALSO | COLOPHON |
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curs_getcchar(3X) curs_getcchar(3X)
getcchar, setcchar - Get a wide character string and rendition
from a cchar_t or set a cchar_t from a wide-character string
#include <curses.h>
int getcchar(
const cchar_t *wcval,
wchar_t *wch,
attr_t *attrs,
short *color_pair,
void *opts );
int setcchar(
cchar_t *wcval,
const wchar_t *wch,
const attr_t attrs,
short color_pair,
const void *opts );
getcchar
The getcchar function gets a wide-character string and rendition
from a cchar_t argument. When wch is not a null pointer, the
getcchar function does the following:
• Extracts information from a cchar_t value wcval
• Stores the character attributes in the location pointed to by
attrs
• Stores the color-pair in the location pointed to by
color_pair
• Stores the wide-character string, characters referenced by
wcval, into the array pointed to by wch.
When wch is a null pointer, the getcchar function does the
following:
• Obtains the number of wide characters pointed to by wcval
• Does not change the data referenced by attrs or color_pair
setcchar
The setcchar function initializes the location pointed to by
wcval by using:
• The character attributes in attrs
• The color pair in color_pair
• The wide-character string pointed to by wch. The string must
be L'\0' terminated, contain at most one spacing character,
which must be the first.
Up to CCHARW_MAX-1 nonspacing characters may follow.
Additional nonspacing characters are ignored.
The string may contain a single control character instead.
In that case, no nonspacing characters are allowed.
X/Open Curses documents the opts argument as reserved for future
use, saying that it must be null. This implementation uses that
parameter in ABI 6 for the functions which have a color-pair
parameter to support extended color pairs:
• For functions which modify the color, e.g., setcchar, if
opts is set it is treated as a pointer to int, and used to
set the color pair instead of the short pair parameter.
• For functions which retrieve the color, e.g., getcchar, if
opts is set it is treated as a pointer to int, and used to
retrieve the color pair as an int value, in addition
retrieving it via the standard pointer to short parameter.
The wcval argument may be a value generated by a call to setcchar
or by a function that has a cchar_t output argument. If wcval is
constructed by any other means, the effect is unspecified.
When wch is a null pointer, getcchar returns the number of wide
characters referenced by wcval, including one for a trailing
null.
When wch is not a null pointer, getcchar returns OK upon
successful completion, and ERR otherwise.
Upon successful completion, setcchar returns OK. Otherwise, it
returns ERR.
The CCHARW_MAX symbol is specific to ncurses. X/Open Curses does
not provide details for the layout of the cchar_t structure. It
tells what data are stored in it:
• a spacing character (wchar_t, i.e., 32-bits).
• non-spacing characters (again, wchar_t's).
• attributes (at least 16 bits, inferred from the various ACS-
and WACS-flags).
• color pair (at least 16 bits, inferred from the unsigned
short type).
The non-spacing characters are optional, in the sense that zero
or more may be stored in a cchar_t. XOpen/Curses specifies a
limit:
Implementations may limit the number of non-spacing
characters that can be associated with a spacing character,
provided any limit is at least 5.
The Unix implementations at the time follow that limit:
• AIX 4 and OSF1 4 use the same declaration with an array of 5
non-spacing characters z and a single spacing character c.
• HP-UX 10 uses an opaque structure with 28 bytes, which is
large enough for the 6 wchar_t values.
• Solaris xpg4 curses uses a single array of 6 wchar_t values.
This implementation's cchar_t was defined in 1995 using 5 for the
total of spacing and non-spacing characters (CCHARW_MAX). That
was probably due to a misreading of the AIX 4 header files,
because the X/Open Curses document was not generally available at
that time. Later (in 2002), this detail was overlooked when
beginning to implement the functions using the structure.
In practice, even four non-spacing characters may seem enough.
X/Open Curses documents possible uses for non-spacing characters,
including using them for ligatures between characters (a feature
apparently not supported by any curses implementation). Unicode
does not limit the (analogous) number of combining characters, so
some applications may be affected.
Functions: curs_attr(3X), curs_color(3X), curses(3X), wcwidth(3).
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have
a bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨https://github.com/mirror/ncurses.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2023-03-12.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
curs_getcchar(3X)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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