NAME

       getcchar, setcchar - convert between a wide-character string and a curses complex character string

SYNOPSIS

       #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 );

DESCRIPTION

   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 non-spacing characters may follow.  Additional non-spacing characters are ignored.

           The  string  may contain a single control character instead.  In that case, no non-spacing characters
           are allowed.

RETURN VALUE

       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.

NOTES

       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.

EXTENSIONS

       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.

PORTABILITY

       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.

SEE ALSO

       ncurses(3NCURSES), attr(3NCURSES), color(3NCURSES), wcwidth(3)