Provided by: ncurses-doc_6.2-0ubuntu2_all bug


       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 advanced.  They are analogous to
       putchar(3) in stdio(3).  If the advance is at the right margin:

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

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

       ·   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:

       ·   Backspace  moves  the  cursor one character left; at the left edge of a window it does

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

       ·   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.

       ·   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 control 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 another using inch(3X) and addch.)  See the attr(3NCURSES)
       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  performance  gain  may  be  seen  by  using  these routines instead of their

   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 configuration 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  successful  completion,  unless
       otherwise noted in the preceding routine descriptions.

       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 locale.

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

       ·   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.

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

       ·   X/Open  Curses  (issues  2  through  7)  has a typographical error for the ACS_LANTERN
           symbol, equating its “VT100+ Character” to I (capital I), while the header  files  for
           SVr4 curses and the various implementations use i (lowercase).

           None  of  the  terminal  descriptions  on  Unix  platforms use uppercase-I, except for
           Solaris  (i.e.,  screen's  terminal  description,  apparently  based  on  the   X/Open
           documentation  around 1995).  On the other hand, the terminal description gs6300 (AT&T
           PC6300 with EMOTS Terminal 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(3NCURSES).

       The displayed values for the ACS_ and WACS_ constants depend on

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

       ·   whether the locale uses UTF-8 encoding.

       In  certain  cases,  the  terminal  is unable to display line-drawing characters 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-character
       information (attributes and color) was separated from the character 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 behavior:

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

       ·   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 curses_variables(3NCURSES) 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.


       ncurses(3NCURSES),  attr(3NCURSES),  clear(3NCURSES),  inch(3NCURSES),  outopts(3NCURSES),
       refresh(3NCURSES), curses_variables(3NCURSES), putc(3).

       Comparable  functions  in  the  wide-character  (ncursesw)  library   are   described   in