addch(3ncurses)
NAME
addch, waddch, mvaddch, mvwaddch, echochar, wechochar - add a character
(with attributes) to a curses window, then advance the cursor
SYNOPSIS
#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);
DESCRIPTION
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 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 nothing.
* 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 and addch.) See the attr(3NCURSES) page for values
of predefined video attribute constants that can be usefully OR'ed into
characters.
Echoing characters
The echochar and wechochar routines are equivalent to a call to addch
followed by a call to refresh, 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
equivalents.
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.
Name Default Description
ACS_BLOCK # solid square block
ACS_BOARD # board of squares
ACS_BTEE + bottom tee
ACS_BULLET o bullet
ACS_CKBOARD : checker board (stipple)
ACS_DARROW v arrow pointing down
ACS_DEGREE ' degree symbol
ACS_DIAMOND + diamond
ACS_GEQUAL > greater-than-or-equal-to
ACS_HLINE - horizontal line
ACS_LANTERN # lantern symbol
ACS_LARROW < arrow pointing left
ACS_LEQUAL < less-than-or-equal-to
ACS_LLCORNER + lower left-hand corner
ACS_LRCORNER + lower right-hand corner
ACS_LTEE + left tee
ACS_NEQUAL ! not-equal
ACS_PI * greek pi
ACS_PLMINUS # plus/minus
ACS_PLUS + plus
ACS_RARROW > arrow pointing right
ACS_RTEE + right tee
ACS_S1 - scan line 1
ACS_S3 - scan line 3
ACS_S7 - scan line 7
ACS_S9 _ scan line 9
ACS_STERLING f pound-sterling symbol
ACS_TTEE + top tee
ACS_UARROW ^ arrow pointing up
ACS_ULCORNER + upper left-hand corner
ACS_URCORNER + upper right-hand corner
ACS_VLINE | vertical line
RETURN VALUE
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.
NOTES
Note that addch, mvaddch, mvwaddch, and echochar may be macros.
PORTABILITY
All these functions are described in the XSI Curses standard, Issue 4.
The defaults specified for forms-drawing characters apply in the POSIX
locale.
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 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)).
The TABSIZE variable is implemented in some versions of curses, but is
not part of X/Open curses.
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.
SEE ALSO
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 add_wch(3NCURSES).
addch(3NCURSES)
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