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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
+ <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>
<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 posi-
- tion, 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><H3><a name="h3-Attributes">Attributes</a></H3><PRE>
- The following bit-masks may be AND-ed with characters returned by
- <STRONG>winch</STRONG>.
-
- <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
+ <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><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
- Functions with a "mv" prefix first perform a cursor movement using
- <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
- the window pointer is null.
+ These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
- The <STRONG>winch</STRONG> function does not return an error if the window contains
- characters larger than 8-bits (255). Only the low-order 8 bits of the
- character are used by <STRONG>winch</STRONG>.
+ 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-NOTES">NOTES</a></H2><PRE>
- Note that all of these routines may be macros.
-
-
-</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- These functions are described in the XSI Curses standard, Issue 4.
- Very old systems (before standardization) provide a different function
- with the same name:
-
- <STRONG>o</STRONG> The <STRONG>winch</STRONG> function was part of the original BSD curses library,
- which stored a 7-bit character combined with the <EM>standout</EM>
- attribute.
-
- In BSD curses, <STRONG>winch</STRONG> returned only the character (as an integer)
- with the <EM>standout</EM> attribute removed.
+</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.
- <STRONG>o</STRONG> System V curses added support for several video attributes which
- could be combined with characters in the window.
+ 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.
- Reflecting this improvement, the function was altered to return the
- character combined with all video attributes in a <STRONG>chtype</STRONG> value.
- X/Open Curses does not specify the size and layout of attributes, color
- and character values in <STRONG>chtype</STRONG>; it is implementation-dependent. This
- implementation uses 8 bits for character values. An application using
- more bits, e.g., a Unicode value, should use the wide-character equiva-
- lents to these functions.
+</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-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.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>
- gives an overview of the WINDOW and <STRONG>chtype</STRONG> data types.
+ <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="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
- goes into more detail, pointing out portability problems and con-
- straints on the use of <STRONG>chtype</STRONG> for returning window information.
+ <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_in_wch.3x.html">curs_in_wch(3x)</A></STRONG>
- describes comparable functions for the wide-character (ncursesw)
- library.
-
- <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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