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+ * @Id: curs_inch.3x,v 1.54 2024/05/18 20:07:52 tom Exp @
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-<H1 class="no-header">curs_inch 3x</H1>
+<H1 class="no-header">curs_inch 3x 2024-05-18 ncurses 6.5 Library calls</H1>
<PRE>
-<STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>
<STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>
+<STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>
Library calls <STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>
-</PRE>
-<H2><a name="h2-NAME">NAME</a></H2><PRE>
- <STRONG>inch</STRONG>, <STRONG>winch</STRONG>, <STRONG>mvinch</STRONG>, <STRONG>mvwinch</STRONG> - get a character and
- attributes from a <STRONG>curses</STRONG> window
+</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
+ <STRONG>inch</STRONG>, <STRONG>winch</STRONG>, <STRONG>mvinch</STRONG>, <STRONG>mvwinch</STRONG> - get a <EM>curses</EM> character from a window
-</PRE>
-<H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
+</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>chtype</STRONG> <STRONG>inch(void);</STRONG>
- <STRONG>chtype</STRONG> <STRONG>winch(WINDOW</STRONG> <STRONG>*win);</STRONG>
- <STRONG>chtype</STRONG> <STRONG>mvinch(int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x);</STRONG>
- <STRONG>chtype</STRONG> <STRONG>mvwinch(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x);</STRONG>
+ <STRONG>chtype</STRONG> <STRONG>winch(WINDOW</STRONG> <STRONG>*</STRONG> <EM>win</EM><STRONG>);</STRONG>
+ <STRONG>chtype</STRONG> <STRONG>mvinch(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>);</STRONG>
+ <STRONG>chtype</STRONG> <STRONG>mvwinch(WINDOW</STRONG> <STRONG>*</STRONG> <EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>);</STRONG>
-</PRE>
-<H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
- These routines return the character, of type <STRONG>chtype</STRONG>, at
- the current position in the named window. If any
- attributes are set for that position, their values are
- OR'ed into the value returned. Constants defined in
- <STRONG><curses.h></STRONG> can be used with the <STRONG>&</STRONG> (logical AND) operator
- to extract the character or attributes alone.
+</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
+ <STRONG>winch</STRONG> returns the <EM>curses</EM> character, including its attributes and color
+ pair identifier, at the cursor position in the window <EM>win</EM>. Subsection
+ "Video Attributes" of <STRONG><A HREF="curs_attr.3x.html">attron(3x)</A></STRONG> explains how to extract these data
+ from a <EM>chtype</EM>. <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG> describes the variants of this function.
-</PRE>
-<H3><a name="h3-Attributes">Attributes</a></H3><PRE>
- The following bit-masks may be AND-ed with characters
- returned by <STRONG>winch</STRONG>.
+</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
+ These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
- <STRONG>A_CHARTEXT</STRONG> Bit-mask to extract character
- <STRONG>A_ATTRIBUTES</STRONG> Bit-mask to extract attributes
- <STRONG>A_COLOR</STRONG> Bit-mask to extract color-pair field information
+ In <EM>ncurses</EM>, <STRONG>winch</STRONG> returns <STRONG>ERR</STRONG> if <EM>win</EM> is <STRONG>NULL</STRONG>.
+ Functions prefixed with "mv" first perform cursor movement and fail if
+ the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.
-</PRE>
-<H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
- Functions with a "mv" prefix first perform a cursor move-
- ment using <STRONG>wmove</STRONG>, and return an error if the position is
- outside the window, or if the window pointer is null.
+</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
+ <STRONG>inch</STRONG>, <STRONG>mvinch</STRONG>, and <STRONG>mvwinch</STRONG> may be implemented as macros.
-</PRE>
-<H2><a name="h2-NOTES">NOTES</a></H2><PRE>
- Note that all of these routines may be macros.
+ These functions do not return an error if the window contains cells of
+ <EM>curses</EM> complex characters; that is, if they contain characters with
+ codes wider than eight bits (or greater than 255 as an unsigned decimal
+ integer). They instead extract only the low-order eight bits of the
+ character code from the cell.
-</PRE>
-<H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- These functions are described in the XSI Curses standard,
- Issue 4.
+</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
+ X/Open Curses, Issue 4 describes these functions. It specifies no
+ error conditions for them.
-</PRE>
-<H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ The original <EM>curses</EM> in 4BSD (1980) defined <EM>winch</EM> as a macro accessing
+ the <EM>WINDOW</EM> structure member representing character cell data, at that
+ time a <EM>char</EM>, containing only a 7-bit ASCII character code and a
+ "standout" attribute bit, the only one the library supported.
+
+ SVr2 <EM>curses</EM> (1984) extended this approach, widening the character code
+ to eight bits and permitting several attributes to be combined with it
+ by storing them together in a <EM>chtype</EM>, an alias of <EM>unsigned</EM> <EM>short</EM>.
+ Because a macro was used, its value was not type-checked as a function
+ return value could have been. Goodheart documented SVr3 (1987) <EM>winch</EM>
+ as returning an <EM>int</EM>. SVr3.1's (1987) <EM>chtype</EM> became an alias of
+ <EM>unsigned</EM> <EM>long</EM>, using 16 bits for the character code and widening the
+ type in practical terms to 32 bits, as 64-bit Unix systems were not yet
+ in wide use, and fixed-width integral types would not be standard until
+ ISO C99. SVr3.2 (1988) added a 6-bit color pair identifier alongside
+ the attributes.
+
+ X/Open Curses does not specify the sizes of the character code or color
+ pair identifier, nor the quantity of attribute bits, in <EM>chtype</EM>; these
+ are implementation-dependent. <EM>ncurses</EM> uses eight bits for the
+ character code. An application requiring a wider character type, for
+ instance to represent Unicode, should use the wide-character
+ counterparts of these functions.
+
- Comparable functions in the wide-character (ncursesw)
- library are described in <STRONG><A HREF="curs_in_wch.3x.html">curs_in_wch(3x)</A></STRONG>.
+</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
+ <STRONG><A HREF="curs_in_wch.3x.html">curs_in_wch(3x)</A></STRONG> describes comparable functions of the <EM>ncurses</EM> library
+ in its wide-character configuration (<EM>ncursesw</EM>).
+ <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_instr.3x.html">curs_instr(3x)</A></STRONG>
- <STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>
+
+ncurses 6.5 2024-05-18 <STRONG><A HREF="curs_inch.3x.html">curs_inch(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-Attributes">Attributes</a></li>
-</ul>
-</li>
+<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</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>
</ul>
</div>
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