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curs_addch(3X)							curs_addch(3X)

       addch, waddch, mvaddch, mvwaddch, echochar, wechochar - add a character
       (with attributes) to a curses window, then advance the cursor

       #include	<curses.h>

       int addch(const chtype ch);
       int waddch(WINDOW *win, const chtype ch);
       int mvaddch(int y, int x, const chtype ch);
       int mvwaddch(WINDOW *win, int y,	int x, const chtype ch);
       int echochar(const chtype ch);
       int wechochar(WINDOW *win, const	chtype ch);

   Adding characters
       The addch, waddch, mvaddch and mvwaddch routines	put the	 character  ch
       into the	given window at	its current window position, which is then ad-
       vanced.	They are analogous to putchar(3) in stdio(3).  If the  advance
       is at the right margin:

       o   The cursor automatically wraps to the beginning of the next line.

       o   At  the  bottom of the current scrolling region, and	if scrollok is
	   enabled, the	scrolling region is scrolled up	one line.

       o   If scrollok is not enabled, writing a character at the lower	 right
	   margin  succeeds.   However,	an error is returned because it	is not
	   possible to wrap to a new line

       If ch is	a tab, newline,	carriage return	or backspace,  the  cursor  is
       moved appropriately within the window:

       o   Backspace  moves the	cursor one character left; at the left edge of
	   a window it does nothing.

       o   Carriage return moves the cursor to the window left margin  on  the
	   current line.

       o   Newline  does  a clrtoeol, then moves the cursor to the window left
	   margin on the next line, scrolling the window if on the last	line.

       o   Tabs	are considered to be at	every eighth column.  The tab interval
	   may be altered by setting the TABSIZE variable.

       If  ch  is  any	other  control	character, it is drawn in ^X notation.
       Calling winch after adding a control  character	does  not  return  the
       character  itself, but instead returns the ^-representation of the con-
       trol character.

       Video attributes	can be combined	with a character  argument  passed  to
       addch  or  related  functions by	logical-ORing them into	the character.
       (Thus, text, including attributes, can be copied	from one place to  an-
       other using inch(3X) and	addch.)	 See the curs_attr(3X) page for	values
       of predefined video attribute constants that can	be usefully OR'ed into

   Echoing characters
       The  echochar  and wechochar routines are equivalent to a call to addch
       followed	by a call to refresh(3X), or a call to waddch  followed	 by  a
       call  to	wrefresh.  The knowledge that only a single character is being
       output is used and, for non-control characters, a considerable  perfor-
       mance gain may be seen by using these routines instead of their equiva-

   Line	Graphics
       The following variables may be used to add line drawing	characters  to
       the  screen  with  routines of the addch	family.	 The default character
       listed below is used if the acsc	capability does	not define a terminal-
       specific	 replacement  for it, or if the	terminal and locale configura-
       tion requires Unicode but the library is	unable to use Unicode.

       The names are taken from	VT100 nomenclature.

       ACS	      ACS	acsc   Glyph
       Name	      Default	char   Name
       ACS_BLOCK      #		0      solid square block
       ACS_BOARD      #		h      board of	squares
       ACS_BTEE	      +		v      bottom tee
       ACS_BULLET     o		~      bullet
       ACS_CKBOARD    :		a      checker board (stipple)
       ACS_DARROW     v		.      arrow pointing down
       ACS_DEGREE     '		f      degree symbol
       ACS_DIAMOND    +		`      diamond
       ACS_GEQUAL     >		>      greater-than-or-equal-to
       ACS_HLINE      -		q      horizontal line
       ACS_LANTERN    #		i      lantern symbol
       ACS_LARROW     <		,      arrow pointing left
       ACS_LEQUAL     <		y      less-than-or-equal-to
       ACS_LLCORNER   +		m      lower left-hand corner
       ACS_LRCORNER   +		j      lower right-hand	corner
       ACS_LTEE	      +		t      left tee
       ACS_NEQUAL     !		|      not-equal
       ACS_PI	      *		{      greek pi
       ACS_PLMINUS    #		g      plus/minus
       ACS_PLUS	      +		n      plus
       ACS_RARROW     >		+      arrow pointing right
       ACS_RTEE	      +		u      right tee
       ACS_S1	      -		o      scan line 1
       ACS_S3	      -		p      scan line 3
       ACS_S7	      -		r      scan line 7
       ACS_S9	      _		s      scan line 9
       ACS_STERLING   f		}      pound-sterling symbol
       ACS_TTEE	      +		w      top tee
       ACS_UARROW     ^		-      arrow pointing up
       ACS_ULCORNER   +		l      upper left-hand corner
       ACS_URCORNER   +		k      upper right-hand	corner
       ACS_VLINE      |		x      vertical	line

       All routines return the integer ERR upon	failure	and OK on success (the
       SVr4  manuals specify only "an integer value other than ERR") upon suc-
       cessful completion, unless otherwise noted in the preceding routine de-

       Functions  with	a  "mv"	 prefix	 first perform a cursor	movement using
       wmove, and return an error if the position is outside the window, or if
       the window pointer is null.

       Note that addch,	mvaddch, mvwaddch, and echochar	may be macros.

       All  these functions are	described in the XSI Curses standard, Issue 4.
       The defaults specified for forms-drawing	characters apply in the	 POSIX

   ACS Symbols
       X/Open Curses states that the ACS_ definitions are char constants.  For
       the wide-character implementation (see curs_add_wch), there are	analo-
       gous  WACS_  definitions	which are cchar_t constants.  Some implementa-
       tions are problematic:

       o   Some	implementations	define the ACS symbols to a constant (such  as
	   Solaris), while others define those to entries in an	array.

	   This	 implementation	uses an	array acs_map, as done in SVr4 curses.
	   NetBSD also uses an array, actually named _acs_char,	with a #define
	   for compatibility.

       o   HPUX	curses equates some of the ACS_	symbols	to the analogous WACS_
	   symbols as if the ACS_ symbols were wide  characters.   The	misde-
	   fined  symbols  are the arrows and other symbols which are not used
	   for line-drawing.

       o   X/Open Curses (issues 2 through 7) has a  typographical  error  for
	   the ACS_LANTERN symbol, equating its	"VT100+	Character" to I	(capi-
	   tal I), while the header files for SVr4 curses and the various  im-
	   plementations use i (lowercase).

	   None	 of the	terminal descriptions on Unix platforms	use uppercase-
	   I, except for Solaris (i.e.,	screen's terminal description,	appar-
	   ently based on the X/Open documentation around 1995).  On the other
	   hand, the terminal description gs6300 (AT&T PC6300 with EMOTS  Ter-
	   minal Emulator) uses	lowercase-i.

       Some  ACS  symbols  (ACS_S3,  ACS_S7,  ACS_LEQUAL,  ACS_GEQUAL, ACS_PI,
       ACS_NEQUAL, ACS_STERLING) were not documented in	any publicly  released
       System  V.   However,  many  publicly  available	terminfos include acsc
       strings in which	their key characters (pryz{|})	are  embedded,	and  a
       second-hand  list  of  their  character descriptions has	come to	light.
       The ACS-prefixed	names for them were invented for ncurses(3X).

       The displayed values for	the ACS_ and WACS_ constants depend on

       o   the library configuration, i.e., ncurses versus ncursesw, where the
	   latter  is  capable	of displaying Unicode while the	former is not,

       o   whether the locale uses UTF-8 encoding.

       In certain cases, the terminal is unable	to display line-drawing	 char-
       acters except by	using UTF-8 (see the discussion	of NCURSES_NO_UTF8_ACS
       in ncurses(3X)).

   Character Set
       X/Open Curses assumes that the parameter	passed to  waddch  contains  a
       single  character.   As	discussed in curs_attr(3X), that character may
       have been more than eight bits in an SVr3 or SVr4  implementation,  but
       in  the	X/Open Curses model, the details are not given.	 The important
       distinction between SVr4	curses and X/Open Curses is that the non-char-
       acter information (attributes and color)	was separated from the charac-
       ter information which is	packed in a chtype to pass to waddch.

       In this implementation,	chtype	holds  an  eight-bit  character.   But
       ncurses	allows	multibyte  characters  to be passed in a succession of
       calls to	waddch.	 The other implementations do not do this; a  call  to
       waddch  passes  exactly	one  character which may be rendered as	one or
       more cells on the screen	depending on whether it	is printable.

       Depending on the	locale settings, ncurses will inspect the byte	passed
       in  each	 call  to waddch, and check if the latest call will continue a
       multibyte sequence.  When a character is	complete, ncurses displays the
       character and moves to the next position	in the screen.

       If  the	calling	 application  interrupts  the succession of bytes in a
       multibyte character by moving the current location (e.g., using wmove),
       ncurses discards	the partially built character, starting	over again.

       For  portability	to other implementations, do not rely upon this	behav-

       o   check if a character	can be represented as a	 single	 byte  in  the
	   current locale before attempting call waddch, and

       o   call	wadd_wch for characters	which cannot be	handled	by waddch.

       The  TABSIZE  variable  is  implemented	in  SVr4 and other versions of
       curses, but is not part of X/Open curses	 (see  curs_variables(3X)  for
       more details).

       If ch is	a carriage return, the cursor is moved to the beginning	of the
       current row of the window.  This	is true	of other implementations,  but
       is not documented.

       curses(3X),  curs_attr(3X),  curs_clear(3X),  curs_inch(3X),  curs_out-
       opts(3X), curs_refresh(3X), curs_variables(3X), putc(3).

       Comparable functions in the wide-character (ncursesw) library  are  de-
       scribed in curs_add_wch(3X).



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