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Copyright 1989 AT&T
Portions Copyright (c) 2001, Sun Microsystems, Inc. All Rights Reserved.
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curses - CRT screen handling and optimization package

cc [ flag... ] file.. .-lcurses [ library... ]
#include <curses.h>

The curses library routines give the user a terminal-independent method of updating character screens with reasonable optimization.

The curses package allows: overall screen, window and pad manipulation; output to windows and pads; reading terminal input; control over terminal and curses input and output options; environment query routines; color manipulation; use of soft label keys; terminfo access; and access to low-level curses routines.

To initialize the routines, the routine initscr() or newterm() must be called before any of the other routines that deal with windows and screens are used. The routine endwin() must be called before exiting. To get character-at-a-time input without echoing (most interactive, screen oriented programs want this), the following sequence should be used:

initscr,cbreak,noecho;

Most programs would additionally use the sequence:

nonl,intrflush(stdscr,FALSE),keypad(stdscr,TRUE);

Before a curses program is run, the tab stops of the terminal should be set and its initialization strings, if defined, must be output. This can be done by executing the tput init command after the shell environment variable TERM has been exported. (See terminfo(4) for further details.)

The curses library permits manipulation of data structures, called windows, which can be thought of as two-dimensional arrays of characters representing all or part of a CRT screen. A default window called stdscr, which is the size of the terminal screen, is supplied. Others may be created with newwin(3CURSES).

Windows are referred to by variables declared as WINDOW *. These data structures are manipulated with routines described on 3CURSES pages (whose names begin "curs_"). Among which the most basic routines are move(3CURSES) and addch(3CURSES). More general versions of these routines are included with names beginning with w, allowing the user to specify a window. The routines not beginning with w affect stdscr.

After using routines to manipulate a window, refresh(3CURSES) is called, telling curses to make the user's CRT screen look like stdscr. The characters in a window are actually of type chtype, (character and attribute data) so that other information about the character may also be stored with each character.

Special windows called pads may also be manipulated. These are windows which are not constrained to the size of the screen and whose contents need not be completely displayed. See curs_pad(3CURSES) for more information.

In addition to drawing characters on the screen, video attributes and colors may be included, causing the characters to show up in such modes as underlined, in reverse video, or in color on terminals that support such display enhancements. Line drawing characters may be specified to be output. On input, curses is also able to translate arrow and function keys that transmit escape sequences into single values. The video attributes, line drawing characters, and input values use names, defined in <curses.h>, such as A_REVERSE, ACS_HLINE, and KEY_LEFT.

If the environment variables LINES and COLUMNS are set, or if the program is executing in a window environment, line and column information in the environment will override information read by terminfo. This would effect a program running in an AT&T 630 layer, for example, where the size of a screen is changeable.

If the environment variable TERMINFO is defined, any program using curses checks for a local terminal definition before checking in the standard place. For example, if TERM is set to att4424, then the compiled terminal definition is found in

/usr/share/lib/terminfo/a/att4424.

(The `a' is copied from the first letter of att4424 to avoid creation of huge directories.) However, if TERMINFO is set to $HOME/myterms, curses first checks

$HOME/myterms/a/att4424,

and if that fails, it then checks

/usr/share/lib/terminfo/a/att4424.

This is useful for developing experimental definitions or when write permission in /usr/share/lib/terminfo is not available.

The integer variables LINES and COLS are defined in <curses.h> and will be filled in by initscr with the size of the screen. The constants TRUE and FALSE have the values 1 and 0, respectively.

The curses routines also define the WINDOW * variable curscr which is used for certain low-level operations like clearing and redrawing a screen containing garbage. The curscr can be used in only a few routines.

The number of bytes and the number of columns to hold a character from the supplementary character set is locale-specific (locale category LC_CTYPE) and can be specified in the character class table.

For editing, operating at the character level is entirely appropriate. For screen formatting, arbitrary movement of characters on screen is not desirable.

Overwriting characters (addch, for example) operates on a screen level. Overwriting a character by a character that requires a different number of columns may produce orphaned columns. These orphaned columns are filled with background characters.

Inserting characters (insch, for example) operates on a character level (that is, at the character boundaries). The specified character is inserted right before the character, regardless of which column of a character the cursor points to. Before insertion, the cursor position is adjusted to the first column of the character.

As with inserting characters, deleting characters (delch, for example) operates on a character level (that is, at the character boundaries). The character at the cursor is deleted whichever column of the character the cursor points to. Before deletion, the cursor position is adjusted to the first column of the character.

A multi-column character cannot be put on the last column of a line. When such attempts are made, the last column is set to the background character. In addition, when such an operation creates orphaned columns, the orphaned columns are filled with background characters.

Overlapping and overwriting a window follows the operation of overwriting characters around its edge. The orphaned columns, if any, are handled as in the character operations.

The cursor is allowed to be placed anywhere in a window. If the insertion or deletion is made when the cursor points to the second or later column position of a character that holds multiple columns, the cursor is adjusted to the first column of the character before the insertion or deletion.

Many curses routines have two or more versions. The routines prefixed with w require a window argument. The routines prefixed with p require a pad argument. Those without a prefix generally use stdscr.

The routines prefixed with mv require an x and y coordinate to move to before performing the appropriate action. The mv routines imply a call to move(3CURSES) before the call to the other routine. The coordinate y always refers to the row (of the window), and x always refers to the column. The upper left-hand corner is always (0,0), not (1,1).

The routines prefixed with mvw take both a window argument and x and y coordinates. The window argument is always specified before the coordinates.

In each case, win is the window affected, and pad is the pad affected; win and pad are always pointers to type WINDOW

Option setting routines require a Boolean flag bf with the value TRUE or FALSE; bf is always of type bool. The variables ch and attrs below are always of type chtype. The types WINDOW, SCREEN, bool, and chtype are defined in <curses.h>. The type TERMINAL is defined in <term.h>. All other arguments are integers.

The following table lists each curses routine and the name of the manual page on which it is described.

curses Routine Name

addch

addchnstr

addchstr

addnstr

addnwstr

addstr

addwch

addwchnstr

addwchstr

addwstr

adjcurspos

attroff

attron

attrset

baudrate

beep

bkgd

bkgdset

border

box

can_change_color

cbreak

clear

clearok

clrtobot

clrtoeol

color_content

copywin

curs_set

def_prog_mode

def_shell_mode

del_curterm

delay_output

delch

deleteln

delscreen

delwin

derwin

doupdate

dupwin

echo

echochar

echowchar

endwin

erase

erasechar

filter

flash

flushinp

getbegyx

getch

getmaxyx

getnwstr

getparyx

getstr

getsyx

getwch

getwin

getwstr

getyx

halfdelay

has_colors

has_ic

has_il

idcok

idlok

immedok

inch

inchnstr

inchstr

init_color

init_pair

initscr

innstr

innwstr

insch

insdelln

insertln

insnstr

insnwstr

insstr

instr

inswch

inswstr

intrflush

inwch

inwchnstr

inwchstr

inwstr

is_linetouched

is_wintouched

isendwin

keyname

keypad

killchar

leaveok

longname

meta

move

movenextch

moveprevch

mvaddch

mvaddchnstr

mvaddchstr

mvaddnstr

mvaddnwstr

mvaddstr

mvaddwch

mvaddwchnstr

mvaddwchstr

mvaddwstr

mvcur

mvdelch

mvderwin

mvgetch

mvgetnwstr

mvgetstr

mvgetwch

mvgetwstr

mvinch

mvinchnstr

mvinchstr

mvinnstr

mvinnwstr

mvinsch

mvinsnstr

mvinsnwstr

mvinsstr

mvinstr

mvinswch

mvinswstr

mvinwch

mvinwchnstr

mvinwchstr

mvinwstr

mvprintw

mvscanw

mvwaddch

mvwaddchnstr

mvwaddchstr

mvwaddnstr

mvwaddnwstr

mvwaddstr

mvwaddwch

mvwaddwchnstr

mvwaddwchstr

mvwaddwstr

mvwdelch

mvwgetch

mvwgetnwstr

mvwgetstr

mvwgetwch

mvwgetwstr

mvwin

mvwinch

mvwinchnstr

mvwinchstr

mvwinnstr

mvwinnwstr

mvwinsch

mvwinsnstr

mvwinsstr

mvwinstr

mvwinswch

mvwinswstr

mvwinwch

mvwinwchnstr

mvwinwchstr

mvwinwstr

mvwprintw

mvwscanw

napms

newpad

newterm

newwin

nl

nocbreak

nodelay

noecho

nonl

noqiflush

noraw

notimeout

overlay

overwrite

pair_content

pechochar

pechowchar

pnoutrefresh

prefresh

printw

putp

putwin

qiflush

raw

redrawwin

refresh

reset_prog_mode

reset_shell_mode

resetty

restartterm

ripoffline

savetty

scanw

scr_dump

scr_init

scr_restore

scr_set

scroll

scrollok

set_curterm

set_term

setscrreg

setsyx

setterm

setupterm

slk_attroff

slk_attron

slk_attrset

slk_clear

slk_init

slk_label

slk_noutrefresh

slk_refresh

slk_restore

slk_set

slk_touch

srcl

standend

standout

start_color

subpad

subwin

syncok

termattrs

termname

tgetent

tgetflag

tgetnum

tgetstr

tgoto

tigetflag

tigetnum

tigetstr

timeout

touchline

touchwin

tparm

tputs

typeahead

unctrl

ungetch

ungetwch

untouchwin

use_env

vidattr

vidputs

vwprintw

vwscanw

waddch

waddchnstr

waddchstr

waddnstr

waddnwstr

waddstr

waddwch

waddwchnstr

waddwchstr

waddwstr

wadjcurspos

wattroff

wattron

wattrset

wbkgd

wbkgdset

wborder

wclear

wclrtobot

wclrtoeol

wcursyncup

wdelch

wdeleteln

wechochar

wechowchar

werase

wgetch

wgetnstr

wgetnwstr

wgetstr

wgetwch

wgetwstr

whline

winch

winchnstr

winchstr

winnstr

winnwstr

winsch

winsdelln

winsertln

winsnstr

winsnwstr

winsstr

winstr

winswch

winswstr

winwch

winwchnstr

winwchstr

winwstr

wmove

wmovenextch

wmoveprevch

wnoutrefresh

wprintw

wredrawln

wrefresh

wscanw

wscrl

wsetscrreg

wstandend

wstandout

wsyncdown

wsyncup

wtimeout

wtouchln

wvline

Routines that return an integer return ERR upon failure and an integer value other than ERR upon successful completion, unless otherwise noted in the routine descriptions.

All macros return the value of the w version, except setscrreg(), wsetscrreg(), getyx(), getbegyx(), and getmaxyx(). The return values of setscrreg(), wsetscrreg(), getyx(), getbegyx(), and getmaxyx() are undefined (that is, these should not be used as the right-hand side of assignment statements).

Routines that return pointers return NULL on error.

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	Unsafe

curses(3XCURSES), libcurses(3LIB), libcurses(3XCURSES), terminfo(4), attributes(5)

The header <curses.h> automatically includes the headers <stdio.h> and <unctrl.h>.