man page(1) manual page

NAME

curs_addch: addch, waddch, mvaddch, mvwaddch, echochar, wechochar - add a character (with attributes) to a curses window, then advance the cursor

int addch(chtype ch);
int waddch(WINDOW *win, chtype ch);
int mvaddch(int y, int x, chtype ch);
int mvwaddch(WINDOW *win, int y, int x, chtype ch);
int echochar(chtype ch);
int wechochar(WINDOW *win, chtype ch);

DESCRIPTION

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, 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, 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 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.)

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 curs_attr(3X) page for values of predefined video attribute constants that can be usefully ORed into 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 doesn't define a terminal-specific replacement for it (but see the EXTENSIONS section below). The names are taken from VT100 nomenclature.

ACS_BLOCK

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_S - 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

# solid square block

ACS_S3 - scan line 3

ACS_S7 - scan line 7

ACS_LEQUAL < lessthan-or-equal-to

ACS_GEQUAL > greater-than-orequal-to

ACS_PI * greek pi

ACS_NEQUAL ! notequal

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, mvaddch, mvwaddch, and echochar may be macros.

EXTENSIONS

The following extended curses 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, 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 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 secondhand list of their character descriptions has come to light. The ACS-prefixed names for them were invented for ncurses(3X).