curs_addch()

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);

The addch(3), waddch(3), mvaddch(3) and mvwaddch(3) 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 the stdio package.

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, if scrollok is enabled, the scrolling region is scrolled up one line.

If ch is a tab, newline, 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. Newline does a clrtoeol(3), 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.

If ch is any control character other than tab, newline, or backspace, it is drawn in ^X notation. Calling winch(3) after adding a control character does not return the character itself, but instead returns the ^-representation of the control character. (To emit control characters literally, use echochar(3).)

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

The echochar(3) and wechochar(3) routines are equivalent to a call to addch(3) followed by a call to refresh(3), or a call to waddch(3) followed by a call to wrefresh(3). 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 doesn't define a terminal-specific replacement for it (but see the EXTENSIONS section below). The names are taken from VT100 nomenclature.

Name	Default	Description
ACS_ULCORNER	+	upper left-hand corner
ACS_LLCORNER	+	lower left-hand corner
ACS_URCORNER	+	upper right-hand corner
ACS_LRCORNER	+	lower right-hand corner
ACS_RTEE	+	right tee
ACS_LTEE	+	left tee
ACS_BTEE	+	bottom tee
ACS_TTEE	+	top tee
ACS_HLINE	-	horizontal line
ACS_VLINE	\|	vertical line
ACS_PLUS	+	plus
ACS_S1	-	scan line 1
ACS_S9	_	scan line 9
ACS_DIAMOND	+	diamond
ACS_CKBOARD	:	checker board (stipple)
ACS_DEGREE	'	degree symbol
ACS_PLMINUS	#	plus/minus
ACS_BULLET	o	bullet
ACS_LARROW	<	arrow pointing left
ACS_RARROW	>	arrow pointing right
ACS_DARROW	v	arrow pointing down
ACS_UARROW	^	arrow pointing up
ACS_BOARD	#	board of squares
ACS_LANTERN	#	lantern symbol
ACS_BLOCK	#	solid square block
ACS_S3	-	scan line 3
ACS_S7	-	scan line 7
ACS_LEQUAL	<	less-than-or-equal-to
ACS_GEQUAL	>	greater-than-or-equal-to
ACS_PI	*	greek pi
ACS_NEQUAL	!	not-equal
ACS_STERLING	f	pound-sterling symbol

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.

NOTES

Note that addch(3), mvaddch(3), mvwaddch(3), and echochar(3) may be macros.

EXTENSIONS

The following extended curses(3) features are available only on PC-clone consoles and compatible terminals obeying the ANSI.SYS de-facto standard for terminal control sequences. They are not part of XSI curses.

The attribute A_ALTCHARSET actually forces literal display of PC ROM characters including the high-half graphics. Your console driver may still capture or translate a few (such as ESC) but this feature should give you access to the card-suit characters, up and down-arrow, and most others in the range 0-32. (In a terminfo entry designed for use with ncurses(3), the high-half characters are obtained using this attribute with an ACSC string in which the second of each pair is a high-half character.)
Giving wechochar(3) an argument with its high bit set will produce the corresponding high-half ASCII graphic (SVr4 curses also has this feature but does not document it). A control-character argument, however, will not typically produce the corresponding graphic; characters such as CR, NL, FF and TAB are typically interpreted by the console driver itself, and ESC will be interpreted as the leader of a control sequence.

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.

The seven ACS symbols starting with ACS_S3 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