ncurses(3NCURSES) Library calls ncurses(3NCURSES)
NAME
ncurses - character-cell terminal interface with optimized output
SYNOPSIS
#include <curses.h>
DESCRIPTION
The “new curses” library offers the programmer a terminal-independent
means of reading keyboard and mouse input and writing to character-cell
displays with output optimized to minimize screen updates. ncurses re-
places the curses libraries from System V Release 4 Unix (“SVr4”) and
4.4BSD Unix, the development of which ceased in the 1990s. This docu-
ment describes ncurses version 6.5 (patch 20250216).
ncurses permits control of the terminal screen's contents; abstraction
and subdivision thereof with windows and pads; acquisition of keyboard
and mouse events; selection of color and rendering attributes (such as
bold or underline); the definition and use of soft label keys; access to
the terminfo terminal capability database; a termcap compatibility in-
terface; and an abstraction of the system's API for manipulating the
terminal (such as termios(3)).
ncurses implements the interface described by X/Open Curses Issue 7. In
many behavioral details not standardized by X/Open, ncurses emulates the
curses library of SVr4 and provides numerous useful extensions.
ncurses man pages employ several sections to clarify matters of usage
and interoperability with other curses implementations.
• “NOTES” describes issues and caveats of which any user of the
ncurses API should be aware, such as limitations on the size of an
underlying integral type or the availability of a preprocessor macro
exclusive of a function definition (which prevents its address from
being taken). This section also describes implementation details of
significance to the programmer but which are not standardized.
• “EXTENSIONS” presents ncurses innovations beyond the X/Open Curses
standard and/or the SVr4 curses implementation. They are termed ex-
tensions to indicate that they cannot be implemented solely by using
the library API, but require access to the library's internal state.
• “PORTABILITY” discusses matters (beyond the exercise of extensions)
that should be considered when writing to a curses standard, or for
multiple implementations.
• “HISTORY” examines points of detail in ncurses and other curses im-
plementations over the decades of their development, particularly
where precedent or inertia have frustrated better design (and, in a
few cases, where such inertia has been overcome).
A curses application must be linked with the library; use the -lncurses
option to your compiler or linker. A debugging version of the library
may be available; if so, link with it using -lncurses_g. (Your system
integrator may have installed these libraries such that you can use the
options -lcurses and -lcurses_g, respectively.) The ncurses_g library
logs events describing ncurses actions to a file called trace in the
current directory. See section “ALTERNATE CONFIGURATIONS” below.
Application Structure
A curses application uses information from the system locale;
setlocale(3) prepares it for curses library calls.
setlocale(LC_ALL, "");
If the locale is not thus initialized, the library assumes that charac-
ters are printable as in ISO 8859-1, to work with certain legacy pro-
grams. You should initialize the locale; do not expect consistent be-
havior from the library when the locale has not been set up.
initscr(3NCURSES) or newterm(3NCURSES) must be called to initialize
curses before use of any functions that access or manipulate windows or
screens.
To get character-at-a-time input without echoing—most interactive,
screen-oriented programs want this—use the following sequence.
initscr(); cbreak(); noecho();
Most applications would perform further setup as follows.
noqiflush();
keypad(stdscr, TRUE);
A curses program then often enters an event loop of some sort. Call
endwin(3NCURSES) before exiting.
Overview
A curses library abstracts the terminal with a SCREEN data structure,
and represents all or part of its display with WINDOW structures. Dis-
tinct properties apply to each; for example, the line discipline of a
typical Unix terminal driver is in one of three modes: raw, cbreak, or
canonical (“cooked”). In curses, the line discipline is a property of
the screen, applying identically to all windows associated with it.
A window is a rectangular grid of character cells, addressed by line and
column coordinates (y, x), with the upper left corner as (0, 0). A win-
dow called stdscr, the same size as the terminal screen, is always
available. Create others with newwin(3NCURSES).
A curses library does not manage overlapping windows (but see below).
You can either use stdscr to manage one screen-filling window, or tile
the screen into non-overlapping windows and not use stdscr at all. Mix-
ing the two approaches will result in unpredictable and undesired ef-
fects.
Functions permit manipulation of a window and the cursor identifying the
cell within it at which the next operation will occur. Among those, the
most basic are move(3NCURSES) and addch(3NCURSES): these place the cur-
sor within and write a character to stdscr, respectively.
Frequent changes to the terminal screen can cause unpleasant flicker or
inefficient use of the communication channel to the device, so as a rule
the library does not update it automatically. Therefore, after using
curses functions to accumulate a set of desired updates that make sense
to present together, call refresh(3NCURSES) to tell the library to make
the user's screen look like stdscr. The library optimizes its output by
computing a minimal volume of operations to mutate the screen from its
state at the previous refresh to the new one. Effective optimization
demands accurate information about the terminal device: the management
of such information is the province of the terminfo(3NCURSES) API, a
feature of every standard curses implementation.
Special windows called pads may also be manipulated. These are not con-
strained to the size of the terminal screen and their contents need not
be completely displayed. See pad(3NCURSES).
Many terminals support configuration of character cell foreground and
background colors as well as attributes, which cause characters to ren-
der in such modes as boldfaced, underlined, or in reverse video. See
attr(3NCURSES).
curses predefines constants for a small set of forms-drawing graphics
corresponding to the DEC Alternate Character Set (ACS), a feature of
VT100 and other terminals. See addch(3NCURSES).
curses is implemented using the operating system's terminal driver; key
events are received not as scan codes but as byte sequences. The driver
reports graphical keycaps (alphanumeric and punctuation keys, and the
space) as-is. Everything else, including the tab, enter/return, keypad,
arrow, and function keys, appears to curses as a control character or a
multibyte escape sequence. curses can translate the latter into unique
key codes. See keypad(3NCURSES) and getch(3NCURSES).
ncurses provides reimplementations of the SVr4 panel(3NCURSES),
form(3FORM), and menu(3MENU) libraries; they permit overlapping windows
and ease construction of user interfaces with curses.
Initialization
The selection of an appropriate value of TERM in the process environment
is essential to correct curses and terminfo library operation. A well-
configured system selects a correct TERM value automatically; tset(1)
may assist with troubleshooting exotic situations.
If you change the terminal type, export the shell's TERM variable, then
run tset(1) or the “tput init” command. See subsection “Tabs and Ini-
tialization” of terminfo(5).
If the environment variables LINES and COLUMNS are set, or if the curses
program is executing in a graphical windowing environment, the informa-
tion obtained thence overrides that obtained by terminfo. An ncurses
extension supports resizable terminal displays; see wresize(3NCURSES).
If the environment variable TERMINFO is defined, a curses program checks
first for a terminal type description in the location it identifies.
TERMINFO is useful for developing type descriptions or when write per-
mission to /etc/terminfo is not available.
See section “ENVIRONMENT” below.
Naming Conventions
curses offers many functions in variant forms using a regular set of al-
ternatives to the name of an elemental one. Those prefixed with “w” re-
quire a WINDOW pointer argument; those with a “mv” prefix first perform
cursor movement using wmove(3NCURSES); a “mvw” prefix indicates both.
The “w” function is typically the elemental one; the removal of this
prefix usually indicates operation on stdscr.
Four functions prefixed with “p” require a pad argument; see below.
In function synopses, ncurses man pages apply the following names to pa-
rameters. We introduce the character types in the next subsection.
bf a bool (TRUE or FALSE)
c a char or int
ch a chtype
wc a wchar_t or wint_t
wch a cchar_t
win pointer to a WINDOW
pad pointer to a WINDOW that is a pad
pair a foreground/background color pair identifier
Wide and Non-wide Character Configurations
This man page primarily surveys functions that appear in any configura-
tion of the library. There are two common configurations; see section
“ALTERNATE CONFIGURATIONS” below.
ncurses is the library in its “non-wide” configuration, handling only
eight-bit characters. It stores a character combined with at-
tributes and a color pair identifier in a chtype datum, which
is often an alias of int. A string of curses characters is
similar to a C char string; a chtype string ends with an inte-
gral 0, the null curses character.
Attributes and a color pair identifier (with no corresponding
character) can be stored in variables of chtype or attr_t
type. In either case, they are accessed via an integral bit
mask.
Each cell of a WINDOW is stored as a chtype. X/Open Curses
does not specify the sizes of the character code or color pair
identifier, nor the quantity of attribute bits, in chtype;
these are implementation-dependent. ncurses uses eight bits
for the character code. An application requiring a wider
character type, for instance to represent Unicode, should use
the wide-character API.
ncursesw is the library in its “wide” configuration, which handles
character encodings requiring a larger data type than char (a
byte-sized type) can represent. It provides additional func-
tions that complement those in the non-wide library where the
size of the underlying character type is significant. A some-
what regular naming convention relates many of the wide vari-
ants to their non-wide counterparts; where a non-wide function
name contains “ch” or “str”, prefix it with “_w” to obtain the
wide counterpart. For example, waddch becomes wadd_wch. An-
other exception is ins_nwstr (and its variants), spelled thus
instead of “insn_wstr”. (Exceptions that add only “w” com-
prise addwstr, inwstr, and their variants.)
This convention is inapplicable to some non-wide function
names, so other transformations are used for the wide configu-
ration: the window background management function “bkgd” be-
comes “bkgrnd”; the window border-drawing and -clearing func-
tions are suffixed with “_set”; and character attribute manip-
ulation functions like “attron” become “attr_on”.
cchar_t is a curses complex character and corresponds to the
non-wide configuration's chtype. It is a structure
type because it requires more storage than a standard
scalar type offers. A character code may not be rep-
resentable as a char, and moreover more than one
character may occupy a cell (as with accent marks and
other diacritics). Each character is of type
wchar_t; a complex character contains one spacing
character and zero or more non-spacing characters
(see below). A string of complex characters ends
with a cchar_t whose wchar_t member is the null wide
character. Attributes and a color pair identifier
are stored in separate fields of the structure, not
combined into an integer as in chtype.
Each cell of a WINDOW is stored as a cchar_t.
setcchar(3NCURSES) and getcchar(3NCURSES) store and retrieve
cchar_t data.
The wide library API of ncurses depends on two data types
standardized by ISO C95.
wchar_t stores a wide character. Like chtype, it may be an
alias of int. Depending on the character encoding, a
wide character may be spacing, meaning that it occu-
pies a character cell by itself and typically accom-
panies cursor advancement, or non-spacing, meaning
that it occupies the same cell as a spacing charac-
ter, is often regarded as a “modifier” of the base
glyph with which it combines, and typically does not
advance the cursor.
wint_t can store a wchar_t or the constant WEOF, analogously
to the int-sized character manipulation functions of
ISO C and its constant EOF.
Function Name Index
The following table lists the curses functions provided in the non-wide
and wide APIs and the corresponding man pages that describe them. Those
flagged with “*” are ncurses-specific, neither described by X/Open
Curses nor present in SVr4.
curses Function Name Man Page
───────────────────────────────────────────────────
COLOR_PAIR color(3NCURSES)
PAIR_NUMBER color(3NCURSES)
add_wch add_wch(3NCURSES)
add_wchnstr add_wchstr(3NCURSES)
add_wchstr add_wchstr(3NCURSES)
addch addch(3NCURSES)
addchnstr addchstr(3NCURSES)
addchstr addchstr(3NCURSES)
addnstr addstr(3NCURSES)
addnwstr addwstr(3NCURSES)
addstr addstr(3NCURSES)
addwstr addwstr(3NCURSES)
alloc_pair new_pair(3NCURSES)*
assume_default_colors default_colors(3NCURSES)*
attr_get attr(3NCURSES)
attr_off attr(3NCURSES)
attr_on attr(3NCURSES)
attr_set attr(3NCURSES)
attroff attr(3NCURSES)
attron attr(3NCURSES)
attrset attr(3NCURSES)
baudrate termattrs(3NCURSES)
beep beep(3NCURSES)
bkgd bkgd(3NCURSES)
bkgdset bkgd(3NCURSES)
bkgrnd bkgrnd(3NCURSES)
bkgrndset bkgrnd(3NCURSES)
border border(3NCURSES)
border_set border_set(3NCURSES)
box border(3NCURSES)
box_set border_set(3NCURSES)
can_change_color color(3NCURSES)
cbreak inopts(3NCURSES)
chgat attr(3NCURSES)
clear clear(3NCURSES)
clearok outopts(3NCURSES)
clrtobot clear(3NCURSES)
clrtoeol clear(3NCURSES)
color_content color(3NCURSES)
color_set attr(3NCURSES)
copywin overlay(3NCURSES)
curs_set kernel(3NCURSES)
curses_trace trace(3NCURSES)*
curses_version extensions(3NCURSES)*
def_prog_mode kernel(3NCURSES)
def_shell_mode kernel(3NCURSES)
define_key define_key(3NCURSES)*
del_curterm terminfo(3NCURSES)
delay_output util(3NCURSES)
delch delch(3NCURSES)
deleteln deleteln(3NCURSES)
delscreen initscr(3NCURSES)
delwin window(3NCURSES)
derwin window(3NCURSES)
doupdate refresh(3NCURSES)
dupwin window(3NCURSES)
echo inopts(3NCURSES)
echo_wchar add_wch(3NCURSES)
echochar addch(3NCURSES)
endwin initscr(3NCURSES)
erase clear(3NCURSES)
erasechar termattrs(3NCURSES)
erasewchar termattrs(3NCURSES)
exit_curses memleaks(3NCURSES)*
exit_terminfo memleaks(3NCURSES)*
extended_color_content color(3NCURSES)*
extended_pair_content color(3NCURSES)*
extended_slk_color slk(3NCURSES)*
filter util(3NCURSES)
find_pair new_pair(3NCURSES)*
flash beep(3NCURSES)
flushinp util(3NCURSES)
free_pair new_pair(3NCURSES)*
get_escdelay threads(3NCURSES)*
get_wch get_wch(3NCURSES)
get_wstr get_wstr(3NCURSES)
getattrs attr(3NCURSES)
getbegx legacy(3NCURSES)*
getbegy legacy(3NCURSES)*
getbegyx getyx(3NCURSES)
getbkgd bkgd(3NCURSES)
getbkgrnd bkgrnd(3NCURSES)
getcchar getcchar(3NCURSES)
getch getch(3NCURSES)
getcurx legacy(3NCURSES)*
getcury legacy(3NCURSES)*
getmaxx legacy(3NCURSES)*
getmaxy legacy(3NCURSES)*
getmaxyx getyx(3NCURSES)
getmouse mouse(3NCURSES)*
getn_wstr get_wstr(3NCURSES)
getnstr getstr(3NCURSES)
getparx legacy(3NCURSES)*
getpary legacy(3NCURSES)*
getparyx getyx(3NCURSES)
getstr getstr(3NCURSES)
getsyx kernel(3NCURSES)
getwin util(3NCURSES)
getyx getyx(3NCURSES)
halfdelay inopts(3NCURSES)
has_colors color(3NCURSES)
has_ic termattrs(3NCURSES)
has_il termattrs(3NCURSES)
has_key getch(3NCURSES)*
has_mouse mouse(3NCURSES)*
hline border(3NCURSES)
hline_set border_set(3NCURSES)
idcok outopts(3NCURSES)
idlok outopts(3NCURSES)
immedok outopts(3NCURSES)
in_wch in_wch(3NCURSES)
in_wchnstr in_wchstr(3NCURSES)
in_wchstr in_wchstr(3NCURSES)
inch inch(3NCURSES)
inchnstr inchstr(3NCURSES)
inchstr inchstr(3NCURSES)
init_color color(3NCURSES)
init_extended_color color(3NCURSES)*
init_extended_pair color(3NCURSES)*
init_pair color(3NCURSES)
initscr initscr(3NCURSES)
innstr instr(3NCURSES)
innwstr inwstr(3NCURSES)
ins_nwstr ins_wstr(3NCURSES)
ins_wch ins_wch(3NCURSES)
ins_wstr ins_wstr(3NCURSES)
insch insch(3NCURSES)
insdelln deleteln(3NCURSES)
insertln deleteln(3NCURSES)
insnstr insstr(3NCURSES)
insstr insstr(3NCURSES)
instr instr(3NCURSES)
intrflush inopts(3NCURSES)
inwstr inwstr(3NCURSES)
is_cbreak inopts(3NCURSES)*
is_cleared opaque(3NCURSES)*
is_echo inopts(3NCURSES)*
is_idcok opaque(3NCURSES)*
is_idlok opaque(3NCURSES)*
is_immedok opaque(3NCURSES)*
is_keypad opaque(3NCURSES)*
is_leaveok opaque(3NCURSES)*
is_linetouched touch(3NCURSES)
is_nl inopts(3NCURSES)*
is_nodelay opaque(3NCURSES)*
is_notimeout opaque(3NCURSES)*
is_pad opaque(3NCURSES)*
is_raw inopts(3NCURSES)*
is_scrollok opaque(3NCURSES)*
is_subwin opaque(3NCURSES)*
is_syncok opaque(3NCURSES)*
is_term_resized resizeterm(3NCURSES)*
is_wintouched touch(3NCURSES)
isendwin initscr(3NCURSES)
key_defined key_defined(3NCURSES)*
key_name util(3NCURSES)
keybound keybound(3NCURSES)*
keyname util(3NCURSES)
keyok keyok(3NCURSES)*
keypad inopts(3NCURSES)
killchar termattrs(3NCURSES)
killwchar termattrs(3NCURSES)
leaveok outopts(3NCURSES)
longname termattrs(3NCURSES)
mcprint print(3NCURSES)*
meta inopts(3NCURSES)
mouse_trafo mouse(3NCURSES)*
mouseinterval mouse(3NCURSES)*
mousemask mouse(3NCURSES)*
move move(3NCURSES)
mvadd_wch add_wch(3NCURSES)
mvadd_wchnstr add_wchstr(3NCURSES)
mvadd_wchstr add_wchstr(3NCURSES)
mvaddch addch(3NCURSES)
mvaddchnstr addchstr(3NCURSES)
mvaddchstr addchstr(3NCURSES)
mvaddnstr addstr(3NCURSES)
mvaddnwstr addwstr(3NCURSES)
mvaddstr addstr(3NCURSES)
mvaddwstr addwstr(3NCURSES)
mvchgat attr(3NCURSES)
mvcur kernel(3NCURSES)
mvdelch delch(3NCURSES)
mvderwin window(3NCURSES)
mvget_wch get_wch(3NCURSES)
mvget_wstr get_wstr(3NCURSES)
mvgetch getch(3NCURSES)
mvgetn_wstr get_wstr(3NCURSES)
mvgetnstr getstr(3NCURSES)
mvgetstr getstr(3NCURSES)
mvhline border(3NCURSES)
mvhline_set border_set(3NCURSES)
mvin_wch in_wch(3NCURSES)
mvin_wchnstr in_wchstr(3NCURSES)
mvin_wchstr in_wchstr(3NCURSES)
mvinch inch(3NCURSES)
mvinchnstr inchstr(3NCURSES)
mvinchstr inchstr(3NCURSES)
mvinnstr instr(3NCURSES)
mvinnwstr inwstr(3NCURSES)
mvins_nwstr ins_wstr(3NCURSES)
mvins_wch ins_wch(3NCURSES)
mvins_wstr ins_wstr(3NCURSES)
mvinsch insch(3NCURSES)
mvinsnstr insstr(3NCURSES)
mvinsstr insstr(3NCURSES)
mvinstr instr(3NCURSES)
mvinwstr inwstr(3NCURSES)
mvprintw printw(3NCURSES)
mvscanw scanw(3NCURSES)
mvvline border(3NCURSES)
mvvline_set border_set(3NCURSES)
mvwadd_wch add_wch(3NCURSES)
mvwadd_wchnstr add_wchstr(3NCURSES)
mvwadd_wchstr add_wchstr(3NCURSES)
mvwaddch addch(3NCURSES)
mvwaddchnstr addchstr(3NCURSES)
mvwaddchstr addchstr(3NCURSES)
mvwaddnstr addstr(3NCURSES)
mvwaddnwstr addwstr(3NCURSES)
mvwaddstr addstr(3NCURSES)
mvwaddwstr addwstr(3NCURSES)
mvwchgat attr(3NCURSES)
mvwdelch delch(3NCURSES)
mvwget_wch get_wch(3NCURSES)
mvwget_wstr get_wstr(3NCURSES)
mvwgetch getch(3NCURSES)
mvwgetn_wstr get_wstr(3NCURSES)
mvwgetnstr getstr(3NCURSES)
mvwgetstr getstr(3NCURSES)
mvwhline border(3NCURSES)
mvwhline_set border_set(3NCURSES)
mvwin window(3NCURSES)
mvwin_wch in_wch(3NCURSES)
mvwin_wchnstr in_wchstr(3NCURSES)
mvwin_wchstr in_wchstr(3NCURSES)
mvwinch inch(3NCURSES)
mvwinchnstr inchstr(3NCURSES)
mvwinchstr inchstr(3NCURSES)
mvwinnstr instr(3NCURSES)
mvwinnwstr inwstr(3NCURSES)
mvwins_nwstr ins_wstr(3NCURSES)
mvwins_wch ins_wch(3NCURSES)
mvwins_wstr ins_wstr(3NCURSES)
mvwinsch insch(3NCURSES)
mvwinsnstr insstr(3NCURSES)
mvwinsstr insstr(3NCURSES)
mvwinstr instr(3NCURSES)
mvwinwstr inwstr(3NCURSES)
mvwprintw printw(3NCURSES)
mvwscanw scanw(3NCURSES)
mvwvline border(3NCURSES)
mvwvline_set border_set(3NCURSES)
napms kernel(3NCURSES)
newpad pad(3NCURSES)
newterm initscr(3NCURSES)
newwin window(3NCURSES)
nl inopts(3NCURSES)
nocbreak inopts(3NCURSES)
nodelay inopts(3NCURSES)
noecho inopts(3NCURSES)
nofilter util(3NCURSES)*
nonl inopts(3NCURSES)
noqiflush inopts(3NCURSES)
noraw inopts(3NCURSES)
notimeout inopts(3NCURSES)
overlay overlay(3NCURSES)
overwrite overlay(3NCURSES)
pair_content color(3NCURSES)
pecho_wchar pad(3NCURSES)
pechochar pad(3NCURSES)
pnoutrefresh pad(3NCURSES)
prefresh pad(3NCURSES)
printw printw(3NCURSES)
putp terminfo(3NCURSES)
putwin util(3NCURSES)
qiflush inopts(3NCURSES)
raw inopts(3NCURSES)
redrawwin refresh(3NCURSES)
refresh refresh(3NCURSES)
reset_color_pairs color(3NCURSES)*
reset_prog_mode kernel(3NCURSES)
reset_shell_mode kernel(3NCURSES)
resetty kernel(3NCURSES)
resize_term resizeterm(3NCURSES)*
resizeterm resizeterm(3NCURSES)*
restartterm terminfo(3NCURSES)
ripoffline kernel(3NCURSES)
savetty kernel(3NCURSES)
scanw scanw(3NCURSES)
scr_dump scr_dump(3NCURSES)
scr_init scr_dump(3NCURSES)
scr_restore scr_dump(3NCURSES)
scr_set scr_dump(3NCURSES)
scrl scroll(3NCURSES)
scroll scroll(3NCURSES)
scrollok outopts(3NCURSES)
set_curterm terminfo(3NCURSES)
set_escdelay threads(3NCURSES)*
set_tabsize threads(3NCURSES)*
set_term initscr(3NCURSES)
setcchar getcchar(3NCURSES)
setscrreg outopts(3NCURSES)
setsyx kernel(3NCURSES)
setupterm terminfo(3NCURSES)
slk_attr slk(3NCURSES)*
slk_attr_off slk(3NCURSES)
slk_attr_on slk(3NCURSES)
slk_attr_set slk(3NCURSES)
slk_attroff slk(3NCURSES)
slk_attron slk(3NCURSES)
slk_attrset slk(3NCURSES)
slk_clear slk(3NCURSES)
slk_color slk(3NCURSES)
slk_init slk(3NCURSES)
slk_label slk(3NCURSES)
slk_noutrefresh slk(3NCURSES)
slk_refresh slk(3NCURSES)
slk_restore slk(3NCURSES)
slk_set slk(3NCURSES)
slk_touch slk(3NCURSES)
slk_wset slk(3NCURSES)
standend attr(3NCURSES)
standout attr(3NCURSES)
start_color color(3NCURSES)
subpad pad(3NCURSES)
subwin window(3NCURSES)
syncok window(3NCURSES)
term_attrs termattrs(3NCURSES)
termattrs termattrs(3NCURSES)
termname termattrs(3NCURSES)
tgetent termcap(3NCURSES)
tgetflag termcap(3NCURSES)
tgetnum termcap(3NCURSES)
tgetstr termcap(3NCURSES)
tgoto termcap(3NCURSES)
tigetflag terminfo(3NCURSES)
tigetnum terminfo(3NCURSES)
tigetstr terminfo(3NCURSES)
timeout inopts(3NCURSES)
tiparm terminfo(3NCURSES)
tiparm_s terminfo(3NCURSES)*
tiscan_s terminfo(3NCURSES)*
touchline touch(3NCURSES)
touchwin touch(3NCURSES)
tparm terminfo(3NCURSES)
tputs termcap(3NCURSES)
tputs terminfo(3NCURSES)
trace trace(3NCURSES)*
typeahead inopts(3NCURSES)
unctrl util(3NCURSES)
unget_wch get_wch(3NCURSES)
ungetch getch(3NCURSES)
ungetmouse mouse(3NCURSES)*
untouchwin touch(3NCURSES)
use_default_colors default_colors(3NCURSES)*
use_env util(3NCURSES)
use_extended_names extensions(3NCURSES)*
use_legacy_coding legacy_coding(3NCURSES)*
use_screen threads(3NCURSES)*
use_tioctl util(3NCURSES)*
use_window threads(3NCURSES)*
vid_attr terminfo(3NCURSES)
vid_puts terminfo(3NCURSES)
vidattr terminfo(3NCURSES)
vidputs terminfo(3NCURSES)
vline border(3NCURSES)
vline_set border_set(3NCURSES)
vw_printw printw(3NCURSES)
vw_scanw scanw(3NCURSES)
vwprintw printw(3NCURSES)
vwscanw scanw(3NCURSES)
wadd_wch add_wch(3NCURSES)
wadd_wchnstr add_wchstr(3NCURSES)
wadd_wchstr add_wchstr(3NCURSES)
waddch addch(3NCURSES)
waddchnstr addchstr(3NCURSES)
waddchstr addchstr(3NCURSES)
waddnstr addstr(3NCURSES)
waddnwstr addwstr(3NCURSES)
waddstr addstr(3NCURSES)
waddwstr addwstr(3NCURSES)
wattr_get attr(3NCURSES)
wattr_off attr(3NCURSES)
wattr_on attr(3NCURSES)
wattr_set attr(3NCURSES)
wattroff attr(3NCURSES)
wattron attr(3NCURSES)
wattrset attr(3NCURSES)
wbkgd bkgd(3NCURSES)
wbkgdset bkgd(3NCURSES)
wbkgrnd bkgrnd(3NCURSES)
wbkgrndset bkgrnd(3NCURSES)
wborder border(3NCURSES)
wborder_set border_set(3NCURSES)
wchgat attr(3NCURSES)
wclear clear(3NCURSES)
wclrtobot clear(3NCURSES)
wclrtoeol clear(3NCURSES)
wcolor_set attr(3NCURSES)
wcursyncup window(3NCURSES)
wdelch delch(3NCURSES)
wdeleteln deleteln(3NCURSES)
wecho_wchar add_wch(3NCURSES)
wechochar addch(3NCURSES)
wenclose mouse(3NCURSES)*
werase clear(3NCURSES)
wget_wch get_wch(3NCURSES)
wget_wstr get_wstr(3NCURSES)
wgetbkgrnd bkgrnd(3NCURSES)
wgetch getch(3NCURSES)
wgetdelay opaque(3NCURSES)*
wgetn_wstr get_wstr(3NCURSES)
wgetnstr getstr(3NCURSES)
wgetparent opaque(3NCURSES)*
wgetscrreg opaque(3NCURSES)*
wgetstr getstr(3NCURSES)
whline border(3NCURSES)
whline_set border_set(3NCURSES)
win_wch in_wch(3NCURSES)
win_wchnstr in_wchstr(3NCURSES)
win_wchstr in_wchstr(3NCURSES)
winch inch(3NCURSES)
winchnstr inchstr(3NCURSES)
winchstr inchstr(3NCURSES)
winnstr instr(3NCURSES)
winnwstr inwstr(3NCURSES)
wins_nwstr ins_wstr(3NCURSES)
wins_wch ins_wch(3NCURSES)
wins_wstr ins_wstr(3NCURSES)
winsch insch(3NCURSES)
winsdelln deleteln(3NCURSES)
winsertln deleteln(3NCURSES)
winsnstr insstr(3NCURSES)
winsstr insstr(3NCURSES)
winstr instr(3NCURSES)
winwstr inwstr(3NCURSES)
wmouse_trafo mouse(3NCURSES)*
wmove move(3NCURSES)
wnoutrefresh refresh(3NCURSES)
wprintw printw(3NCURSES)
wredrawln refresh(3NCURSES)
wrefresh refresh(3NCURSES)
wresize wresize(3NCURSES)*
wscanw scanw(3NCURSES)
wscrl scroll(3NCURSES)
wsetscrreg outopts(3NCURSES)
wstandend attr(3NCURSES)
wstandout attr(3NCURSES)
wsyncdown window(3NCURSES)
wsyncup window(3NCURSES)
wtimeout inopts(3NCURSES)
wtouchln touch(3NCURSES)
wunctrl util(3NCURSES)
wvline border(3NCURSES)
wvline_set border_set(3NCURSES)
ncurses's screen-pointer extension adds additional functions correspond-
ing to many of the above, each with an “_sp” suffix; see
sp_funcs(3NCURSES).
The availability of some extensions is configurable when ncurses is com-
piled; see sections “ALTERNATE CONFIGURATIONS” and “EXTENSIONS” below.
RETURN VALUE
Unless otherwise noted, functions that return integers return the con-
stants OK on success and ERR on failure; see curses_variables(3NCURSES).
Functions that return pointers return NULL on failure. Typically,
ncurses treats a null pointer passed as a function parameter as a fail-
ure. Functions prefixed with “mv” first perform cursor movement and
fail if the position (y, x) is outside the window boundaries.
ENVIRONMENT
The following symbols from the process environment customize the runtime
behavior of ncurses applications. The library may be configured to dis-
regard the variables TERMINFO, TERMINFO_DIRS, TERMPATH, and HOME, if the
user is the superuser (root), or the application uses setuid(2) or
setgid(2).
BAUDRATE
The debugging library checks this variable when the application has
redirected output to a file. ncurses interprets its integral value as
the terminal's line speed in bits per second. If that value is absent
or invalid, ncurses uses 9600. This feature allows developers to con-
struct repeatable test cases that take into account optimization deci-
sions that depend on the terminal's line speed.
CC (command character)
When set, the command_character (cmdch) capability value of loaded term-
info entries changes to the value of this variable. Very few terminfo
entries provide this feature.
Because this name is also used in development environments to store the
C compiler's name, ncurses ignores its value if it is not one character
in length.
COLUMNS
This variable specifies the width of the screen in characters. Applica-
tions running in a windowing environment usually are able to obtain the
width of the window in which they are executing. ncurses enforces an
upper limit of 512 when reading the value. If COLUMNS is not defined
and the terminal's screen size is not available from the terminal dri-
ver, ncurses uses the size specified by the columns (cols) capability of
the terminal type's entry in the terminfo database, if any.
It is important that your application use the correct screen size. Au-
tomatic detection thereof is not always possible because an application
may be running on a host that does not honor NAWS (Negotiations About
Window Size) or as a different user ID than the owner of the terminal
device file. Setting COLUMNS and/or LINES overrides the library's use
of the screen size obtained from the operating system.
The COLUMNS and LINES variables may be specified independently. This
property is useful to circumvent misfeatures of legacy terminal type de-
scriptions; xterm(1) descriptions specifying 65 lines were once notori-
ous. For best results, avoid specifying cols and lines capability codes
in terminfo descriptions of terminal emulators.
use_env(3NCURSES) can disable use of the process environment in deter-
mining the screen size. use_tioctl(3NCURSES) can update COLUMNS and
LINES to match the screen size obtained from system calls or the termi-
nal database.
ESCDELAY
For curses to distinguish the ESC character resulting from a user's
press of the “Escape” key on the input device from one beginning an es-
cape sequence (as commonly produced by function keys), it waits after
receiving the escape character to see if further characters are avail-
able on the input stream within a short interval. A global variable
ESCDELAY stores this interval in milliseconds. The default value of
1000 (one second) is adequate for most uses. This environment variable
overrides it; ncurses enforces an upper limit of 30,000 (30 seconds)
when reading the value.
The most common instance where you may wish to change this value is to
work with a remote host over a slow communication channel. If the host
running a curses application does not receive the characters of an es-
cape sequence in a timely manner, the library can interpret them as mul-
tiple key stroke events.
xterm(1) mouse events are a form of escape sequence; therefore, if your
application makes heavy use of multiple-clicking, you may wish to
lengthen the default value because the delay applies to the composite
multi-click event as well as the individual clicks.
Portable applications should not rely upon the presence of ESCDELAY in
either form, but setting the environment variable rather than the global
variable does not create problems when compiling an application.
If keypad(3NCURSES) is disabled for the curses window receiving input, a
program must disambiguate escape sequences itself.
HOME
ncurses may read and write auxiliary terminal descriptions in .termcap
and .terminfo files in the user's home directory.
LINES
This counterpart to COLUMNS specifies the height of the screen in char-
acters. The corresponding terminfo capability and code is lines. See
the description of the COLUMNS variable above.
MOUSE_BUTTONS_123
(OS/2 EMX port only) OS/2 numbers a three-button mouse inconsistently
with other platforms, such that 1 is the left button, 2 the right, and 3
the middle. This variable customizes the mouse button numbering. Its
value must be three digits 1-3 in any order. By default, ncurses as-
sumes a numbering of “132”.
NCURSES_ASSUMED_COLORS
If set, this variable overrides the ncurses library's compiled-in as-
sumption that the terminal's default colors are white on black; see
default_colors(3NCURSES). Set the foreground and background color val-
ues with this environment variable by assigning it two integer values
separated by a comma, indicating foregound and background color numbers,
respectively.
For example, to tell ncurses not to assume anything about the colors,
use a value of “-1,-1”. To make the default color scheme green on
black, use “2,0”. ncurses accepts integral values from -1 up to the
value of the terminfo max_colors (colors) capability.
NCURSES_CONSOLE2
(MinGW port only) The Console2 program defectively handles the Microsoft
Console API call CreateConsoleScreenBuffer. Applications that use it
will hang. However, it is possible to simulate the action of this call
by mapping coordinates, explicitly saving and restoring the original
screen contents. Setting the environment variable NCGDB has the same
effect.
NCURSES_GPM_TERMS
(Linux only) When ncurses is configured to use the GPM interface, this
variable may list one or more terminal type names, delimited by vertical
bars (|) or colons (:), against which the TERM variable (see below) is
matched. An empty value disables the GPM interface, using ncurses's
built-in support for xterm(1) mouse protocols instead. If the variable
is absent, ncurses attempts to open GPM if TERM contains “linux”.
NCURSES_NO_HARD_TABS
ncurses may use tab characters in cursor movement optimization. In some
cases, your terminal driver may not handle them properly. Set this en-
vironment variable to any value to disable the feature. You can also
adjust your stty(1) settings to avoid the problem.
NCURSES_NO_MAGIC_COOKIE
Many terminals store video attributes as a property of a character cell,
as curses does. Historically, some recorded changes in video attributes
as data that logically occupies character cells on the display, switch-
ing attributes on or off, similarly to tags in a markup language; these
are termed “magic cookies”, and must be subsequently overprinted. If
the terminfo entry for your terminal type does not adequately describe
its handling of magic cookies, set this variable to any value to in-
struct ncurses to disable attributes entirely.
NCURSES_NO_PADDING
Most terminal type descriptions in the terminfo database detail hardware
devices. Many people use curses-based applications in terminal emulator
programs that run in a windowing environment. These programs can dupli-
cate all of the important features of a hardware terminal, but often
lack their limitations. Chief among these absent drawbacks is the prob-
lem of data flow management; that is, limiting the speed of communica-
tion to what the hardware could handle. Unless a hardware terminal is
interfaced into a terminal concentrator (which does flow control), an
application must manage flow itself to prevent overruns and data loss.
A solution that comes at no hardware cost is for an application to pause
after directing a terminal to execute an operation that it performs
slowly, such as clearing the display. Many terminal type descriptions,
including that for the VT100, embed delay specifications in capabili-
ties. You may wish to use these terminal descriptions without paying
the performance penalty. Set NCURSES_NO_PADDING to any value to disable
all but mandatory padding. Mandatory padding is used by such terminal
capabilities as flash_screen (flash).
NCURSES_NO_SETBUF
(Obsolete) Prior to internal changes developed in ncurses 5.9 (patches
20120825 through 20130126), the library used setbuf(3) to enable fully
buffered output when initializing the terminal. This was done, as in
SVr4 curses, to increase performance. For testing purposes, both of
ncurses and of certain applications, this feature was made optional.
Setting this variable disabled output buffering, leaving the output
stream in the original (usually line-buffered) mode.
Nowadays, ncurses performs its own buffering and does not require this
workaround; it does not modify the buffering of the standard output
stream. This approach makes signal handling, as for interrupts, more
robust. A drawback is that certain unconventional programs mixed
stdio(3) calls with ncurses calls and (usually) got the behavior they
expected. This is no longer the case; ncurses does not write to the
standard output file descriptor through a stdio-buffered stream.
As a special case, low-level API calls such as putp(3NCURSES) still use
the standard output stream. High-level curses calls such as
printw(3NCURSES) do not.
NCURSES_NO_UTF8_ACS
At initialization, ncurses inspects the TERM environment variable for
special cases where VT100 forms-drawing characters (and the correspond-
ing alternate character set terminfo capabilities) are known to be un-
supported by terminal types that otherwise claim VT100 compatibility.
Specifically, when running in a UTF-8 locale, the Linux virtual console
device and the GNU screen(1) program ignore them. Set this variable to
a nonzero value to instruct ncurses that the terminal's ACS support is
broken; the library then outputs Unicode code points that correspond to
the forms-drawing characters. Set it to zero (or a non-integer) to dis-
able the special check for terminal type names matching “linux” or
“screen”, directing ncurses to assume that the ACS feature works if the
terminal type description advertises it.
As an alternative to use of this variable, ncurses checks for an ex-
tended terminfo numeric capability U8 that can be compiled using “tic
-x”. Examples follow.
# linux console, if patched to provide working
# VT100 shift-in/shift-out, with corresponding font.
linux-vt100|linux console with VT100 line-graphics,
U8#0, use=linux,
# uxterm with vt100Graphics resource set to false
xterm-utf8|xterm relying on UTF-8 line-graphics,
U8#1, use=xterm,
The two-character name “U8” was chosen to permit its use via ncurses's
termcap interface.
NCURSES_TRACE
At initialization, ncurses (in its debugging configuration) checks for
this variable's presence. If defined with an integral value, the li-
brary calls curses_trace(3NCURSES) with that value as the argument.
TERM
The TERM variable denotes the terminal type. Each is distinct, though
many are similar. It is commonly set by terminal emulators to help ap-
plications find a workable terminal description. Some choose a popular
approximation such as “ansi”, “vt100”, or “xterm” rather than an exact
fit to their capabilities. Not infrequently, an application will have
problems with that approach; for example, a key stroke may not operate
correctly, or produce no effect but seeming garbage characters on the
screen.
Setting TERM has no effect on hardware operation; it affects the way ap-
plications communicate with the terminal. Likewise, as a general rule
(xterm(1) being a rare exception), terminal emulators that allow you to
specify TERM as a parameter or configuration value do not change their
behavior to match that setting.
TERMCAP
If ncurses is configured with termcap support, it checks for a terminal
type description in termcap format if one in terminfo format is not
available. Setting this variable directs ncurses to ignore the usual
termcap database location, /etc/termcap; see TERMPATH below. TERMCAP
should contain either a terminal description (with newlines stripped
out), or a file name indicating where the information required by the
TERM environment variable is stored.
TERMINFO
ncurses can be configured to read terminal type description databases in
various locations using different formats. This variable overrides the
default location.
• Descriptions in terminfo format are normally stored in a directory
tree using subdirectories named for the common first letters of the
terminal types named therein. This is the scheme used in System V.
• If ncurses is configured to use hashed databases, then TERMINFO may
name its location, such as /usr/share/terminfo.db, rather than
/usr/share/terminfo/.
The hashed database uses less disk space and is a little faster than the
directory tree. However, some applications assume the existence of the
directory tree, and read it directly rather than using the terminfo API.
• If ncurses is configured with termcap support, this variable may
contain the location of a termcap file.
• If the value of TERMINFO begins with “hex:” or “b64:”, ncurses uses
the remainder of the value as a compiled terminfo description. You
might produce the base64 format using infocmp(1).
TERMINFO=$(infocmp -0 -Q2 -q)
export TERMINFO
The compiled description is used only if it corresponds to the ter-
minal type identified by TERM.
Setting TERMINFO is the simplest, but not the only, way to direct
ncurses to a terminal database. The search path is as follows.
• the last terminal database to which the running ncurses application
wrote, if any
• the location specified by the TERMINFO environment variable
• $HOME/.terminfo
• locations listed in the TERMINFO_DIRS environment variable
• location(s) configured and compiled into ncurses
• /etc/terminfo:/lib/terminfo:/usr/share/terminfo
• /etc/terminfo
TERMINFO_DIRS
This variable specifies a list of locations, akin to PATH, in which
ncurses searches for the terminal type descriptions described by
TERMINFO above. The list items are separated by colons on Unix and
semicolons on OS/2 EMX. System V terminfo lacks a corresponding fea-
ture; TERMINFO_DIRS is an ncurses extension.
TERMPATH
If TERMCAP does not hold a terminal type description or file name, then
ncurses checks the contents of TERMPATH, a list of locations, akin to
PATH, in which it searches for termcap terminal type descriptions. The
list items are separated by colons on Unix and semicolons on OS/2 EMX.
If both TERMCAP and TERMPATH are unset or invalid, ncurses searches for
the files /etc/termcap, /usr/share/misc/termcap, and $HOME/.termcap, in
that order.
ALTERNATE CONFIGURATIONS
Many different ncurses configurations are possible, determined by the
options given to the configure script when building the library. Run
the script with the --help option to peruse them all. A few are of par-
ticular significance to the application developer employing ncurses.
--disable-overwrite
The standard C preprocessor inclusion for the curses library is as
follows.
#include <curses.h>
This option is used to avoid file name conflicts between ncurses
and an existing curses installation on the system. If ncurses is
installed disabling overwrite, it puts its header files in a subdi-
rectory. Here is an example.
#include <ncurses/curses.h>
Installation also omits a symbolic link that would cause the com-
piler's -lcurses option to link object files with ncurses instead
of the system curses library.
The directory used by this configuration of ncurses is shown in
section “SYNOPSIS” above.
--enable-widec
The configure script renames the library and (if the
--disable-overwrite option is used) puts the header files in a dif-
ferent subdirectory. All of the library names have a “w” appended
to them, i.e., instead of
-lncurses
you link with
-lncursesw
You must also enable the wide-character features in the header file
when compiling for the wide-character library to use the extended
(wide-character) functions. The symbol which enables these fea-
tures has changed since X/Open Curses Issue 4:
• Originally, the wide-character feature required the symbol
_XOPEN_SOURCE_EXTENDED but that was only valid for XPG4 (1996).
• Later, that was deemed conflicting with _XOPEN_SOURCE defined
to 500.
• As of mid-2018, none of the features in this implementation re-
quire a _XOPEN_SOURCE feature greater than 600. However,
X/Open Curses Issue 7 (2009) recommends defining it to 700.
• Alternatively, you can enable the feature by defining
NCURSES_WIDECHAR with the caveat that some other header file
than curses.h may require a specific value for _XOPEN_SOURCE
(or a system-specific symbol).
The curses.h header file installed for the wide-character library
is designed to be compatible with the non-wide library's header.
Only the size of the WINDOW structure differs; few applications re-
quire more than pointers to WINDOWs.
If the headers are installed allowing overwrite, the wide-character
library's headers should be installed last, to allow applications
to be built using either library from the same set of headers.
--with-pthread
The configure script renames the library. All of the library names
have a “t” appended to them (before any “w” added by
--enable-widec).
The global variables such as LINES are replaced by macros to allow
read-only access. At the same time, setter-functions are provided
to set these values. Some applications (very few) may require
changes to work with this convention.
--with-shared
--with-normal
--with-debug
--with-profile
The shared and normal (static) library names differ by their suf-
fixes, e.g., libncurses.so and libncurses.a. The debug and profil-
ing libraries add a “_g” and a “_p” to the root names respectively,
e.g., libncurses_g.a and libncurses_p.a.
--with-termlib
Low-level functions which do not depend upon whether the library
supports wide-characters, are provided in the tinfo library.
By doing this, it is possible to share the tinfo library between
wide/normal configurations as well as reduce the size of the li-
brary when only low-level functions are needed.
Those functions are described in these pages:
• extensions(3NCURSES) - miscellaneous curses extensions
• inopts(3NCURSES) - curses input options
• kernel(3NCURSES) - low-level curses routines
• termattrs(3NCURSES) - curses environment query routines
• termcap(3NCURSES) - curses emulation of termcap
• terminfo(3NCURSES) - curses interface to terminfo database
• util(3NCURSES) - miscellaneous curses utility routines
--with-trace
The trace function normally resides in the debug library, but it is
sometimes useful to configure this in the shared library. Config-
ure scripts should check for the function's existence rather than
assuming it is always in the debug library.
FILES
/usr/share/tabset
tab stop initialization database
/etc/terminfo
compiled terminal capability database
NOTES
X/Open Curses permits most functions it specifies to be made available
as macros as well. ncurses does so
• for functions that return values via their parameters,
• to support obsolete features,
• to reuse functions (for example, those that move the cursor before
another operation), and
• in a few special cases.
If the standard output file descriptor of an ncurses program is redi-
rected to something that is not a terminal device, the library writes
screen updates to the standard error file descriptor. This was an un-
documented feature of SVr3 curses.
See subsection “Header Files” below regarding symbols exposed by inclu-
sion of curses.h.
EXTENSIONS
ncurses enables an application to capture mouse events on certain termi-
nals, including xterm(1); see mouse(3NCURSES).
ncurses provides a means of responding to window resizing events, as
when running in a GUI terminal emulator application such as xterm; see
resizeterm(3NCURSES) and wresize(3NCURSES).
ncurses allows an application to query the terminal for the presence of
a wide variety of special keys; see has_key(3NCURSES).
ncurses extends the fixed set of function key capabilities specified by
X/Open Curses by allowing the application programmer to define addi-
tional key events at runtime; see define_key(3NCURSES),
key_defined(3NCURSES), keybound(3NCURSES), and keyok(3NCURSES).
ncurses can exploit the capabilities of terminals implementing
ISO 6429/ECMA-48 SGR 39 and SGR 49 sequences, which allow an application
to reset the terminal to its original foreground and background colors.
From a user's perspective, the application is able to draw colored text
on a background whose color is set independently, providing better con-
trol over color contrasts. See default_colors(3NCURSES).
An ncurses application can eschew knowledge of SCREEN and WINDOW struc-
ture internals, instead using accessor functions such as
is_cbreak(3NCURSES) and is_scrollok(3NCURSES).
ncurses enables an application to direct its output to a printer at-
tached to the terminal device; see print(3NCURSES).
ncurses offers slk_attr(3NCURSES) as a counterpart of attr_get(3NCURSES)
for soft-label key lines, and extended_slk_color(3NCURSES) as a form of
slk_color(3NCURSES) that can gather color information from them when
many colors are supported.
ncurses permits modification of unctrl(3NCURSES)'s behavior; see
use_legacy_coding(3NCURSES).
Rudimentary support for multi-threaded applications may be available;
see threads(3NCURSES).
Functions that ease the management of multiple screens can be exposed;
see sp_funcs(3NCURSES).
To aid applications to debug their memory usage, ncurses optionally of-
fers functions to more aggressively free memory it dynamically allocates
itself; see memleaks(3NCURSES).
The library facilitates auditing and troubleshooting of its behavior;
see trace(3NCURSES).
Compiling ncurses with the option -DUSE_GETCAP causes it to fall back to
reading /etc/termcap if the terminal setup code cannot find a terminfo
entry corresponding to TERM. Use of this feature is not recommended, as
it essentially includes an entire termcap compiler in the ncurses
startup code, at a cost in memory usage and application launch latency.
PDCurses and NetBSD curses incorporate some ncurses extensions. Indi-
vidual man pages indicate where this is the case.
PORTABILITY
X/Open Curses defines two levels of conformance, “base” and “enhanced”.
The latter includes several additional features, such as wide-character
and color support. ncurses intends base-level conformance with X/Open
Curses, and supports all features of its enhanced level except the untic
utility.
Differences between X/Open Curses and ncurses are documented in the
“PORTABILITY” sections of applicable man pages.
Error Checking
In many cases, X/Open Curses is vague about error conditions, omitting
some of the SVr4 documentation.
Unlike other implementations, ncurses checks pointer parameters, such as
those to WINDOW structures, to ensure that they are not null. This is
done primarily to guard against programmer error. The standard inter-
face does not provide a way for the library to tell an application which
of several possible errors occurred. An application that relies on
ncurses to check its function parameters for validity limits its porta-
bility and robustness.
Padding Differences
In historical curses implementations, delays embedded in the terminfo
capabilities carriage_return (cr), scroll_forward (ind), cursor_left
(cub1), form_feed (ff), and tab (ht) activated corresponding delay bits
in the Unix terminal driver. ncurses performs all padding by sending
NUL bytes to the device. This method is slightly more expensive, but
narrows the interface to the Unix kernel significantly and correspond-
ingly increases the package's portability.
Header Files
The header file curses.h itself includes the header files stdio.h and
unctrl.h.
X/Open Curses has more to say,
The inclusion of curses.h may make visible all symbols from the
headers stdio.h, term.h, termios.h, and wchar.h.
but does not finish the story. A more complete account follows.
• The first curses, in 4BSD, provided a curses.h file.
BSD curses code included curses.h and unctrl.h from an internal
header file curses.ext, where “ext” abbreviated “externs”.
The implementations of printw and scanw used undocumented internal
functions of the standard I/O library (_doprnt and _doscan), but
nothing in curses.h itself relied upon stdio.h.
• SVr2 curses added newterm, which relies upon stdio.h because its
function prototype employs the FILE type.
SVr4 curses added putwin and getwin, which also use stdio.h.
X/Open Curses specifies all three of these functions.
SVr4 curses and X/Open Curses do not require the developer to in-
clude stdio.h before curses.h. Both document use of curses as re-
quiring only curses.h.
As a result, standard curses.h always includes stdio.h.
• X/Open Curses and SVr4 curses are inconsistent with respect to
unctrl.h.
As noted in util(3NCURSES), ncurses includes unctrl.h from curses.h
(as SVr4 does).
• X/Open Curses's comments about term.h and termios.h may refer to HP-
UX and AIX.
HP-UX curses includes term.h from curses.h to declare setupterm in
curses.h, but ncurses and Solaris curses do not.
AIX curses includes term.h and termios.h. Again, ncurses and So-
laris curses do not.
• X/Open Curses says that curses.h may include term.h, but does not
require it to do so.
Some programs use functions declared in both curses.h and term.h,
and must include both header files in the same module. Very old
versions of AIX curses required inclusion of curses.h before term.h.
The header files supplied by ncurses include the standard library
headers required for its declarations, so ncurses's own header files
can be included in any order. For portability even to old AIX sys-
tems, include curses.h before term.h.
• X/Open Curses says “may make visible” because including a header
file does not necessarily make visible all of the symbols in it
(consider #ifdef and similar).
For instance, ncurses's curses.h may include wchar.h if the proper
symbol is defined, and if ncurses is configured for wide-character
support. If wchar.h is included, its symbols may be made visible
depending on the value of the _XOPEN_SOURCE feature test macro.
• X/Open Curses mandates an application's inclusion of one standard C
library header in a special case: stdarg.h before curses.h to proto-
type the functions vw_printw and vw_scanw (as well as the obsolete
vwprintw and vwscanw). Each of these takes a variadic argument
list, a va_list parameter, like that of printf(3).
SVr3 curses introduced the two obsolete functions, and X/Open Curses
the others. In between, SVr4 curses provided for the possibility
that an application might include either varargs.h or stdarg.h.
These represented contrasting approaches to handling variadic argu-
ment lists. The older interface, varargs.h, used a pointer to char
for variadic functions' va_list parameter. Later, the list acquired
its own standard data type, va_list, defined in stdarg.h, empowering
the compiler to check the types of a function call's actual parame-
ters against the formal ones declared in its prototype.
No conforming implementations of X/Open Curses require an applica-
tion to include stdarg.h before curses.h because they either have
allowed for a special type, or, like ncurses, they include stdarg.h
themselves to provide a portable interface.
AUTHORS
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey. Based on pcurses
by Pavel Curtis.
SEE ALSO
curses_variables(3NCURSES), terminfo(5), user_caps(5)
ncurses 6.5 2025-01-18 ncurses(3NCURSES)
Generated by dwww version 1.16 on Sat Oct 3 04:26:51 CEST 2026.