.\"***************************************************************************
-.\" Copyright (c) 2001-2010,2012 Free Software Foundation, Inc. *
+.\" Copyright 2019-2023,2024 Thomas E. Dickey *
+.\" Copyright 2001-2015,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_getcchar.3x,v 1.16 2012/11/03 23:03:59 tom Exp $
-.TH curs_getcchar 3X ""
+.\" $Id: curs_getcchar.3x,v 1.49 2024/04/20 18:55:09 tom Exp $
+.TH curs_getcchar 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.SH NAME
-\fBgetcchar\fP,
-\fBsetcchar\fP \- Get a wide character string and rendition from a \fBcchar_t\fP or set a \fBcchar_t\fP from a wide-character string
+\fB\%getcchar\fP,
+\fB\%setcchar\fP \-
+convert between a wide-character string and a \fIcurses\fR complex character
.SH SYNOPSIS
-\fB#include <curses.h>\fP
-.sp
-\fBint getcchar(\fP
-.br
-.B " const cchar_t *\fIwcval\fP,"
-.br
-.B " wchar_t *\fIwch\fP,"
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fBint getcchar(
+.B " const cchar_t *\fIwch\fP,"
+.B " wchar_t *\fIwc\fP,"
.B " attr_t *\fIattrs\fP,"
-.br
.B " short *\fIcolor_pair\fP,"
-.br
.B " void *\fIopts\fP );"
-.sp
+.PP
.B "int setcchar("
-.br
-.B " cchar_t *\fIwcval\fP,"
-.br
-.B " const wchar_t *\fIwch\fP,"
-.br
+.B " cchar_t *\fIwch\fP,"
+.B " const wchar_t *\fIwc\fP,"
.B " const attr_t \fIattrs\fP,"
-.br
.B " short \fIcolor_pair\fP,"
-.br
-.B " void *\fIopts\fP );"
+.B " const void *\fIopts\fP );"
+.fi
.SH DESCRIPTION
-.PP
+.SS getcchar
The \fBgetcchar\fP function gets a wide-character string
and rendition from a \fBcchar_t\fP argument.
-When \fIwch\fP is not a null pointer,
+When \fIwc\fP is not a null pointer,
the \fBgetcchar\fP function does the following:
.bP
-Extracts information from a \fBcchar_t\fP value \fIwcval\fP
+Extracts information from a \fBcchar_t\fP value \fIwch\fP
.bP
Stores the character attributes in the location pointed to by \fIattrs\fP
.bP
-Stores the color-pair in the location pointed to by \fIcolor_pair\fP
+Stores the color pair in the location pointed to by \fIcolor_pair\fP
.bP
Stores the wide-character string,
-characters referenced by \fIwcval\fP, into the array pointed to by \fIwch\fP.
+characters referenced by \fIwch\fP, into the array pointed to by \fIwc\fP.
.PP
When
-\fIwch\fP
+\fIwc\fP
is a null pointer, the
\fBgetcchar\fP
function does the following:
.bP
-Obtains the number of wide characters pointed to by \fIwcval\fP
+Obtains the number of wide characters pointed to by \fIwch\fP
.bP
Does not change the data referenced by
\fIattrs\fP
or
\fIcolor_pair\fP
-.PP
-The \fBsetcchar\fP function initializes the location pointed to by \fIwcval\fP
+.SS setcchar
+The \fBsetcchar\fP function initializes the location pointed to by \fIwch\fP
by using:
.bP
The character attributes in
The color pair in
\fIcolor_pair\fP
.bP
-The wide-character string pointed to by \fIwch\fP.
-The string must be L'\\0' terminated,
+The wide-character string pointed to by \fIwc\fP.
+The string must be L'\e0' terminated,
contain at most one spacing character,
which must be the first.
.IP
-Up to \fBCCHARW_MAX\fP\-1 nonspacing characters may follow.
-Additional nonspacing characters are ignored.
+Up to \fBCCHARW_MAX\fP\-1 non-spacing characters may follow.
+Additional non-spacing characters are ignored.
.IP
The string may contain a single control character instead.
-In that case, no nonspacing characters are allowed.
-.SH NOTES
-.PP
-The \fIopts\fP argument is reserved for future use.
-Currently, an application must provide a null pointer as \fIopts\fP.
-.PP
-The \fIwcval\fP argument may be a value generated by a call to
-\fBsetcchar\fP or by a function that has a \fBcchar_t\fP output argument.
-If \fIwcval\fP is constructed by any other means, the effect is unspecified.
+In that case, no non-spacing characters are allowed.
.SH RETURN VALUE
-.PP
-When \fIwch\fP is a null pointer,
+When \fIwc\fP is a null pointer,
\fBgetcchar\fP returns the number of wide characters referenced by
-\fIwcval\fP,
+\fIwch\fP,
including one for a trailing null.
.PP
-When \fIwch\fP is not a null pointer,
+When \fIwc\fP is not a null pointer,
\fBgetcchar\fP returns \fBOK\fP upon successful completion,
and \fBERR\fP otherwise.
.PP
Upon successful completion, \fBsetcchar\fP returns \fBOK\fP.
Otherwise, it returns \fBERR\fP.
-.SH SEE ALSO
+.SH NOTES
+The \fIwch\fP argument may be a value generated by a call to
+\fBsetcchar\fP or by a function that has a \fBcchar_t\fP output argument.
+If \fIwch\fP is constructed by any other means, the effect is unspecified.
+.SH EXTENSIONS
+X/Open Curses documents the \fIopts\fP 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:
+.bP
+For functions which modify the color, e.g., \fBsetcchar\fP,
+if \fIopts\fP is set it is treated as a pointer to \fBint\fP,
+and used to set the color pair instead of the \fBshort\fP pair parameter.
+.bP
+For functions which retrieve the color, e.g., \fBgetcchar\fP,
+if \fIopts\fP is set it is treated as a pointer to \fBint\fP,
+and used to retrieve the color pair as an \fBint\fP value,
+in addition retrieving it via the standard pointer to \fBshort\fP parameter.
+.SH PORTABILITY
+The \fBCCHARW_MAX\fP symbol is specific to \fI\%ncurses\fP.
+X/Open Curses does not provide details for the layout of the \fBcchar_t\fP
+structure.
+It tells what data are stored in it:
+.bP
+a spacing character (\fBwchar_t\fP, i.e., 32-bits).
+.bP
+non-spacing characters (again, \fBwchar_t\fP's).
+.bP
+attributes (at least 16 bits, inferred from the various ACS- and WACS-flags).
+.bP
+color pair (at least 16 bits, inferred from the \fBunsigned short\fP type).
+.PP
+The non-spacing characters are optional,
+in the sense that zero or more may be stored in a \fBcchar_t\fP.
+XOpen/Curses specifies a limit:
+.RS 4
+.PP
+Implementations may limit the number of non-spacing characters that can be
+associated with a spacing character, provided any limit is at least 5.
+.RE
.PP
-Functions:
-\fBcurs_attr\fR(3X),
-\fBcurs_color\fR(3X),
-\fBcurses\fR(3X),
-\fBwcwidth\fR(3).
+The Unix implementations at the time follow that limit:
+.bP
+AIX\ 4 and OSF1\ 4 use the same declaration with an array of 5 non-spacing
+characters \fIz\fP and a single spacing character \fIc\fP.
+.bP
+HP-UX\ 10 uses an opaque structure with 28 bytes,
+which is large enough for the 6 \fBwchar_t\fP values.
+.bP
+Solaris \fIxpg4\fP curses uses a single array of 6 \fBwchar_t\fP values.
+.PP
+This implementation's \fBcchar_t\fP was defined in 1995
+using \fB5\fP for the total of spacing and non-spacing characters
+(\fBCCHARW_MAX\fP).
+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.
+.PP
+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.
+.SH SEE ALSO
+\fB\%curses\fP(3X),
+\fB\%curs_attr\fP(3X),
+\fB\%curs_color\fP(3X),
+\fB\%wcwidth\fP(3)
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