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<H1 class="no-header">curs_getcchar 3x 2025-02-23 ncurses 6.6 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_getcchar.3x.html">curs_getcchar(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_getcchar.3x.html">curs_getcchar(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>getcchar</STRONG>, <STRONG>setcchar</STRONG> - convert between a wide-character string and a
<EM>curses</EM> complex character
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>getcchar(const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG> <EM>wch</EM><STRONG>,</STRONG> <STRONG>wchar_t</STRONG> <STRONG>*</STRONG> <EM>wc</EM><STRONG>,</STRONG>
<STRONG>attr_t</STRONG> <STRONG>*</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>setcchar(cchar_t</STRONG> <STRONG>*</STRONG> <EM>wch</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>wchar_t</STRONG> <STRONG>*</STRONG> <EM>wc</EM><STRONG>,</STRONG>
<STRONG>const</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
The <EM>curses</EM> complex character data type <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> is a structure type
comprising a wide-character string, a set of attributes, and a color
pair identifier. The <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> structure is opaque; do not attempt to
access its members directly. The library provides functions to
manipulate this type.
</PRE><H3><a name="h3-getcchar">getcchar</a></H3><PRE>
<STRONG>getcchar</STRONG> destructures a <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> into its components.
If <EM>wc</EM> is not a null pointer, <STRONG>getcchar</STRONG>:
<STRONG>o</STRONG> stores the wide-character string in the <EM>curses</EM> complex character
<EM>wch</EM> into <EM>wc</EM>;
<STRONG>o</STRONG> stores the attributes in <EM>attrs</EM>; and
<STRONG>o</STRONG> stores the color pair identifier in <EM>pair</EM>.
If <EM>wc</EM> is a null pointer, <STRONG>getcchar</STRONG> counts the <EM>wchar</EM><STRONG>_</STRONG><EM>t</EM> wide characters in
<EM>wch</EM>, returns that value, and leaves <EM>attrs</EM> and <EM>pair</EM> unchanged.
</PRE><H3><a name="h3-setcchar">setcchar</a></H3><PRE>
<STRONG>setcchar</STRONG> constructs a <EM>curses</EM> complex character <EM>wch</EM> from the components
<EM>wc</EM>, <EM>attrs</EM>, and <EM>pair</EM>. The wide-character string <EM>wch</EM> must be terminated
with a null wide character <STRONG>L'\0'</STRONG> and must contain at most one spacing
character, which, if present, must be the first wide character in the
string.
Up to <STRONG>CCHARW_MAX</STRONG> - 1 non-spacing characters may follow (see
<STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>). <EM>ncurses</EM> ignores any additional non-spacing
characters.
The string may contain a single control character instead. In that
case, no non-spacing characters are allowed.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
If <STRONG>getcchar</STRONG> is passed a null pointer as its <EM>wc</EM> argument, it returns the
number of wide characters for a given <EM>wch</EM> that it would store in <EM>wc</EM>,
counting a trailing null wide character. If <STRONG>getcchar</STRONG> is not passed a
null pointer as its <EM>wc</EM> argument, it returns <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on
failure.
In <EM>ncurses</EM>, <STRONG>getcchar</STRONG> returns <STRONG>ERR</STRONG> if either <EM>attrs</EM> or <EM>pair</EM> is a null
pointer and <EM>wc</EM> is not.
<STRONG>setcchar</STRONG> returns <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
In <EM>ncurses</EM>, <STRONG>setcchar</STRONG> returns <STRONG>ERR</STRONG> if
<STRONG>o</STRONG> <EM>wch</EM> is a null pointer,
<STRONG>o</STRONG> <EM>wc</EM> starts with a (wide) control character and contains any other
wide characters, or
<STRONG>o</STRONG> <EM>pair</EM> has a negative value.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
<EM>wch</EM> may be a value stored by <STRONG>setcchar</STRONG> or another <EM>curses</EM> function with a
writable <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> argument. If <EM>wch</EM> is constructed by any other means,
the library's behavior is unspecified.
</PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
X/Open Curses documents the <EM>opts</EM> argument as reserved for future use,
saying that it must be a null pointer. The <EM>ncurses</EM> 6 ABI uses it with
functions that have a color pair parameter to support extended color
pairs.
<STRONG>o</STRONG> In functions that assign colors, such as <STRONG>setcchar</STRONG>, if <EM>opts</EM> is not a
null pointer, <EM>ncurses</EM> treats it as a pointer to <EM>int</EM>, and interprets
it instead of the <EM>short</EM> <EM>pair</EM> parameter as a color pair identifier.
<STRONG>o</STRONG> In functions that retrieve colors, such as <STRONG>getcchar</STRONG>, if <EM>opts</EM> is not
a null pointer, <EM>ncurses</EM> treats it as a pointer to <EM>int</EM>, and stores
the retrieved color pair identifier there as well as in the <EM>short</EM>
<EM>pair</EM> parameter (which may therefore undergo a narrowing
conversion).
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
Applications employing <EM>ncurses</EM> extensions should condition their use on
the visibility of the <STRONG>NCURSES_VERSION</STRONG> preprocessor macro.
These functions are described in X/Open Curses Issue 4. It specifies
no error conditions for them.
X/Open Curses does not detail the layout of the <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> structure,
describing only its minimal required contents:
<STRONG>o</STRONG> a spacing wide character (<EM>wchar</EM><STRONG>_</STRONG><EM>t</EM>),
<STRONG>o</STRONG> at least five non-spacing wide characters (<EM>wchar</EM><STRONG>_</STRONG><EM>t</EM>; see below),
<STRONG>o</STRONG> attributes (at least 15 bits' worth, inferred from the count of
specified <EM>WA</EM><STRONG>_</STRONG> constants),
<STRONG>o</STRONG> a color pair identifier (at least 16 bits, inferred from the <EM>short</EM>
type used to encode it).
Non-spacing characters are optional, in the sense that zero or more may
be stored in a <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>. 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.
Then-contemporary Unix implementations adhered to that limit.
<STRONG>o</STRONG> AIX 4 and OSF/1 4 used the same declaration with a single spacing
wide character <EM>c</EM> and an array of 5 non-spacing wide characters <EM>z</EM>.
<STRONG>o</STRONG> HP-UX 10 used an opaque structure of 28 bytes, large enough for 6
<EM>wchar</EM><STRONG>_</STRONG><EM>t</EM> values.
<STRONG>o</STRONG> Solaris <EM>xcurses</EM> uses a single array of 6 <EM>wchar</EM><STRONG>_</STRONG><EM>t</EM> values.
<EM>ncurses</EM> defined its <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> in 1995 using 5 as the <EM>total</EM> of spacing and
non-spacing characters (<STRONG>CCHARW_MAX</STRONG>). 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 work began to implement the functions
using the structure.
In practice, a mere four non-spacing characters may seem adequate.
X/Open Curses documents possible applications of non-spacing
characters, including their use as ligatures (a feature apparently not
supported by any <EM>curses</EM> implementation). Unicode does not limit the
(analogous) number of combining characters in a grapheme cluster; some
applications may be affected. <EM>ncurses</EM> can be compiled with a different
<STRONG>CCHARW_MAX</STRONG> value; doing so alters the library's ABI.
</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
X/Open Curses Issue 4 (1995) initially specified these functions.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>, <STRONG>wcwidth(3)</STRONG>
ncurses 6.6 2025-02-23 <STRONG><A HREF="curs_getcchar.3x.html">curs_getcchar(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-getcchar">getcchar</a></li>
<li><a href="#h3-setcchar">setcchar</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
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