Provided by: ncurses-doc_6.1-1ubuntu1_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

       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 eight bits.  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 some versions of curses, but is not part of  X/Open

       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