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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