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<H1 class="no-header">curs_addch 3x 2024-04-20 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>addch</STRONG>, <STRONG>waddch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, <STRONG>echochar</STRONG>, <STRONG>wechochar</STRONG> - add a <EM>curses</EM>
character to a window and advance the cursor
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>addch(const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>waddch(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>mvaddch(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>mvwaddch(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> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>echochar(const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>wechochar(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
</PRE><H3><a name="h3-Adding-Characters">Adding Characters</a></H3><PRE>
<STRONG>waddch</STRONG> puts the character <EM>ch</EM> at the cursor position of window <EM>win</EM>, then
advances the cursor position, analogously to the standard C library's
<STRONG>putchar(3)</STRONG>. <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG> describes the variants of this function.
If advancement occurs at the right margin,
<STRONG>o</STRONG> the cursor automatically wraps to the beginning of the next line;
and
<STRONG>o</STRONG> at the bottom of the current scrolling region, and if <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG>
is enabled for <EM>win</EM>, the scrolling region scrolls up one line.
If <EM>ch</EM> is a backspace, carriage return, line feed, or tab, the cursor
moves appropriately within the window.
<STRONG>o</STRONG> Backspace moves the cursor one character left; at the left margin
of a window, it does nothing.
<STRONG>o</STRONG> Carriage return moves the cursor to the left margin on the current
line of the window.
<STRONG>o</STRONG> Line feed does a <STRONG><A HREF="curs_clear.3x.html">clrtoeol(3x)</A></STRONG>, then moves the cursor to the left
margin on the next line of the window, and if <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is
enabled for <EM>win</EM>, scrolls the window if the cursor was already on
the last line.
<STRONG>o</STRONG> Tab advances the cursor to the next tab stop (possibly on the next
line); these are placed at every eighth column by default. Alter
the tab interval with the <STRONG>TABSIZE</STRONG> extension; see
<STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>.
If <EM>ch</EM> is any other nonprintable character, it is drawn in printable
form, using the same convention as <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG>.
Calling <STRONG><A HREF="curs_inch.3x.html">winch(3x)</A></STRONG> on the location of a nonprintable character does not
return the character itself, but its <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG> representation.
<EM>ch</EM> may contain rendering and/or color attributes, and others can be
combined with the parameter by logically "or"ing with it. (A character
with its attributes can be copied from place to place using <STRONG><A HREF="curs_inch.3x.html">winch(3x)</A></STRONG>
and <STRONG>waddch</STRONG>.) See <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> for values of predefined video
attribute constants that can be usefully "or"ed with characters.
</PRE><H3><a name="h3-Echoing-Characters">Echoing Characters</a></H3><PRE>
<STRONG>echochar</STRONG> and <STRONG>wechochar</STRONG> are equivalent to calling (<STRONG>w</STRONG>)<STRONG>addch</STRONG> followed by
(<STRONG>w</STRONG>)<STRONG>refresh</STRONG>. <EM>curses</EM> interprets these functions as a hint that only a
single character is being output; for non-control characters, a
considerable performance gain may be enjoyed by employing them.
</PRE><H3><a name="h3-Forms-Drawing-Characters">Forms-Drawing Characters</a></H3><PRE>
<EM>curses</EM> defines macros starting with <STRONG>ACS_</STRONG> that can be used with <STRONG>waddch</STRONG>
to write line-drawing and other special characters to the screen.
<EM>ncurses</EM> terms these <EM>forms-drawing</EM> <EM>characters.</EM> The ACS default listed
below is used if the <STRONG>acs_chars</STRONG> (<STRONG>acsc</STRONG>) <EM>terminfo</EM> capability does not
define a terminal-specific replacement for it, or if the terminal and
locale configuration requires Unicode to access these characters but
the library is unable to use Unicode. The "acsc char" column
corresponds to how the characters are specified in the <STRONG>acs_chars</STRONG> string
capability, and the characters in it may appear on the screen if the
terminal's database entry incorrectly advertises ACS support. The name
"ACS" originates in the Alternate Character Set feature of the DEC
VT100 terminal.
<STRONG>ACS</STRONG> <STRONG>acsc</STRONG>
<STRONG>Symbol</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Glyph</STRONG> <STRONG>Name</STRONG>
------------------------------------------------------------------------
<STRONG>ACS_BLOCK</STRONG> # 0 solid square block
<STRONG>ACS_BOARD</STRONG> # h board of squares
<STRONG>ACS_BTEE</STRONG> + v bottom tee
<STRONG>ACS_BULLET</STRONG> o ~ bullet
<STRONG>ACS_CKBOARD</STRONG> : a checker board (stipple)
<STRONG>ACS_DARROW</STRONG> v . arrow pointing down
<STRONG>ACS_DEGREE</STRONG> ' f degree symbol
<STRONG>ACS_DIAMOND</STRONG> + ` diamond
<STRONG>ACS_GEQUAL</STRONG> > > greater-than-or-equal-to
<STRONG>ACS_HLINE</STRONG> - q horizontal line
<STRONG>ACS_LANTERN</STRONG> # i lantern symbol
<STRONG>ACS_LARROW</STRONG> < , arrow pointing left
<STRONG>ACS_LEQUAL</STRONG> < y less-than-or-equal-to
<STRONG>ACS_LLCORNER</STRONG> + m lower left-hand corner
<STRONG>ACS_LRCORNER</STRONG> + j lower right-hand corner
<STRONG>ACS_LTEE</STRONG> + t left tee
<STRONG>ACS_NEQUAL</STRONG> ! | not-equal
<STRONG>ACS_PI</STRONG> * { greek pi
<STRONG>ACS_PLMINUS</STRONG> # g plus/minus
<STRONG>ACS_PLUS</STRONG> + n plus
<STRONG>ACS_RARROW</STRONG> > + arrow pointing right
<STRONG>ACS_RTEE</STRONG> + u right tee
<STRONG>ACS_S1</STRONG> - o scan line 1
<STRONG>ACS_S3</STRONG> - p scan line 3
<STRONG>ACS_S7</STRONG> - r scan line 7
<STRONG>ACS_S9</STRONG> _ s scan line 9
<STRONG>ACS_STERLING</STRONG> f } pound-sterling symbol
<STRONG>ACS_TTEE</STRONG> + w top tee
<STRONG>ACS_UARROW</STRONG> ^ - arrow pointing up
<STRONG>ACS_ULCORNER</STRONG> + l upper left-hand corner
<STRONG>ACS_URCORNER</STRONG> + k upper right-hand corner
<STRONG>ACS_VLINE</STRONG> | x vertical line
</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.
In <EM>ncurses</EM>, <STRONG>waddch</STRONG> returns <STRONG>ERR</STRONG> if it is not possible to add a complete
character at the cursor position, as when conversion of a multibyte
character to a byte sequence fails, or at least one of the resulting
bytes cannot be added to the window. See section "PORTABILITY" below
regarding the use of <STRONG>waddch</STRONG> with multibyte characters.
<STRONG>waddch</STRONG> can successfully write a character at the bottom right location
of the window. However, <EM>ncurses</EM> returns <STRONG>ERR</STRONG> if <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not
enabled in that event, because it is not possible to wrap to a new
line.
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>
<STRONG>addch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, and <STRONG>echochar</STRONG> may be implemented as macros.
</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.
SVr4 <EM>curses</EM> describes a successful return value only as "an integer
value other than <STRONG>ERR</STRONG>".
The defaults specified for forms-drawing characters apply in the POSIX
locale.
</PRE><H3><a name="h3-ACS-Symbols">ACS Symbols</a></H3><PRE>
X/Open Curses states that the <STRONG>ACS_</STRONG> definitions are <EM>char</EM> constants.
Some implementations are problematic.
<STRONG>o</STRONG> Solaris <EM>curses</EM>, for example, define the ACS symbols as constants;
others define them as elements of an array.
This implementation uses an array, <STRONG>acs_map</STRONG>, as did SVr4 <EM>curses</EM>.
NetBSD also uses an array, actually named <STRONG>_acs_char</STRONG>, with a <STRONG>#define</STRONG>
for compatibility.
<STRONG>o</STRONG> HP-UX <EM>curses</EM> equates some of the <STRONG>ACS_</STRONG> symbols to the analogous
<STRONG>WACS_</STRONG> symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters (see
<STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>). The misdefined symbols are the arrows and
others that are not used for line drawing.
<STRONG>o</STRONG> X/Open Curses (Issues 2 through 7) has a typographical error for
the <STRONG>ACS_LANTERN</STRONG> symbol, equating its "VT100+ Character" to "I"
(capital I), while the header files for SVr4 <EM>curses</EM> and other
implementations use "i" (small i).
None of the terminal descriptions on Unix platforms use uppercase
I, except for Solaris (in its <EM>terminfo</EM> entry for <STRONG>screen(1)</STRONG>,
apparently based on the X/Open documentation around 1995). On the
other hand, its <STRONG>gs6300</STRONG> (AT&T PC6300 with EMOTS Terminal Emulator)
description uses lowercase i.
Some ACS symbols (<STRONG>ACS_S3</STRONG>, <STRONG>ACS_S7</STRONG>, <STRONG>ACS_LEQUAL</STRONG>, <STRONG>ACS_GEQUAL</STRONG>, <STRONG>ACS_PI</STRONG>,
<STRONG>ACS_NEQUAL</STRONG>, and <STRONG>ACS_STERLING</STRONG>) were not documented in any publicly
released System V. However, many publicly available <EM>terminfo</EM> entries
include <STRONG>acsc</STRONG> strings in which their key characters <STRONG>(</STRONG>pryz{|}<STRONG>)</STRONG> are
embedded, and a second-hand list of their character descriptions has
come to light. The <EM>ncurses</EM> developers invented ACS-prefixed names for
them.
The <EM>displayed</EM> values of <STRONG>ACS_</STRONG> constants depend on
<STRONG>o</STRONG> the <EM>ncurses</EM> ABI--for example, wide-character versus non-wide-
character configurations (the former is capable of displaying
Unicode while the latter is not), and
<STRONG>o</STRONG> whether the locale uses UTF-8 encoding.
In certain cases, the terminal is unable to display forms-drawing
characters <EM>except</EM> by using UTF-8; see the discussion of the
<EM>NCURSES</EM><STRONG>_</STRONG><EM>NO</EM><STRONG>_</STRONG><EM>UTF8</EM><STRONG>_</STRONG><EM>ACS</EM> environment variable in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>).
</PRE><H3><a name="h3-Character-Set">Character Set</a></H3><PRE>
X/Open Curses assumes that the parameter passed to <STRONG>waddch</STRONG> contains a
single character. As discussed in <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, that character may
have been more than eight bits wide in an SVr3 or SVr4 implementation,
but in the X/Open Curses model, the details are not given. The
important distinction between SVr4 <EM>curses</EM> and X/Open Curses is that the
latter separates non-character information (attributes and color) from
the character code, which SVr4 packs into a <EM>chtype</EM> for passage to
<STRONG>waddch</STRONG>.
In <EM>ncurses</EM>, <EM>chtype</EM> holds an eight-bit character. But the library
allows a multibyte character to be passed in a succession of calls to
<STRONG>waddch</STRONG>. Other implementations do not; a <STRONG>waddch</STRONG> call transmits exactly
one character, which may be rendered in one or more screen locations
depending on whether it is printable.
Depending on the locale settings, <EM>ncurses</EM> inspects the byte passed in
each <STRONG>waddch</STRONG> call, and checks whether the latest call continues a
multibyte sequence. When a character is <EM>complete</EM>, <EM>ncurses</EM> displays the
character and advances the cursor.
If the calling application interrupts the succession of bytes in a
multibyte character sequence by changing the current location--for
example, with <STRONG><A HREF="curs_move.3x.html">wmove(3x)</A></STRONG>--<EM>ncurses</EM> discards the incomplete character.
For portability to other implementations, do not rely upon this
behavior. Check whether a character can be represented as a single
byte in the current locale.
<STRONG>o</STRONG> If it can, call either <STRONG>waddch</STRONG> or <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG>.
<STRONG>o</STRONG> If it cannot, use only <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG>.
</PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
SVr4 and other versions of <EM>curses</EM> implement the <STRONG>TABSIZE</STRONG> variable, but
X/Open Curses does not specify it (see <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>).
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="curs_add_wch.3x.html">curs_add_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_addchstr.3x.html">curs_addchstr(3x)</A></STRONG>, <STRONG><A HREF="curs_addstr.3x.html">curs_addstr(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>,
<STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>, <STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>,
<STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG>putchar(3)</STRONG>
ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_addch.3x.html">curs_addch(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-Adding-Characters">Adding Characters</a></li>
<li><a href="#h3-Echoing-Characters">Echoing Characters</a></li>
<li><a href="#h3-Forms-Drawing-Characters">Forms-Drawing Characters</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-PORTABILITY">PORTABILITY</a>
<ul>
<li><a href="#h3-ACS-Symbols">ACS Symbols</a></li>
<li><a href="#h3-Character-Set">Character Set</a></li>
<li><a href="#h3-TABSIZE">TABSIZE</a></li>
</ul>
</li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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