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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXTENSIONS | PORTABILITY | HISTORY | SEE ALSO | COLOPHON |
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curs_attr(3X) Library calls curs_attr(3X)
attr_get, wattr_get, attr_set, wattr_set, attr_off, wattr_off,
attr_on, wattr_on, attroff, wattroff, attron, wattron, attrset,
wattrset, chgat, wchgat, mvchgat, mvwchgat, color_set, wcolor_set,
standend, wstandend, standout, wstandout - manipulate attributes
of character cells in curses windows
#include <curses.h>
int attr_get(attr_t *attrs, short *pair, void *opts);
int wattr_get(WINDOW *win, attr_t *attrs, short *pair, void *opts);
int attr_set(attr_t attrs, short pair, void *opts);
int wattr_set(WINDOW *win, attr_t attrs, short pair, void *opts);
int attr_off(attr_t attrs, void *opts);
int wattr_off(WINDOW *win, attr_t attrs, void *opts);
int attr_on(attr_t attrs, void *opts);
int wattr_on(WINDOW *win, attr_t attrs, void *opts);
int attroff(int attrs);
int wattroff(WINDOW *win, int attrs);
int attron(int attrs);
int wattron(WINDOW *win, int attrs);
int attrset(int attrs);
int wattrset(WINDOW *win, int attrs);
int chgat(int n, attr_t attr, short pair, const void *opts);
int wchgat(WINDOW *win,
int n, attr_t attr, short pair, const void *opts);
int mvchgat(int y, int x,
int n, attr_t attr, short pair, const void *opts);
int mvwchgat(WINDOW *win, int y, int x,
int n, attr_t attr, short pair, const void *opts);
int color_set(short pair, void* opts);
int wcolor_set(WINDOW *win, short pair, void* opts);
int standend(void);
int wstandend(WINDOW *win);
int standout(void);
int wstandout(WINDOW *win);
These routines manipulate the current attributes of the named
window, which then apply to all characters that are written into
the window with waddch, waddstr and wprintw. Attributes are a
property of the character, and move with the character through any
scrolling and insert/delete line/character operations. To the
extent possible, they are displayed as appropriate modifications
to the graphic rendition of characters put on the screen.
These routines do not affect the attributes used when erasing
portions of the window. See curs_bkgd(3X) for functions which
modify the attributes used for erasing and clearing.
Window Attributes
There are two sets of functions:
• functions for manipulating the window attributes and color:
wattr_set and wattr_get.
• functions for manipulating only the window attributes (not
color): wattr_on and wattr_off.
The wattr_set function sets the current attributes of the given
window to attrs, with color specified by pair.
Use wattr_get to retrieve attributes for the given window.
Use attr_on and wattr_on to turn on window attributes, i.e.,
values logically “or”-ed together in attr, without affecting other
attributes. Use attr_off and wattr_off to turn off window
attributes, again values logically “or”-ed together in attr,
without affecting other attributes.
Legacy Window Attributes
The X/Open window attribute routines which set or get, turn on or
off are extensions of older routines which assume that color pairs
are logically “or”-ed into the attribute parameter. These newer
routines use similar names, because X/Open simply added an
underscore (_) for the newer names.
The int datatype used in the legacy routines is treated as if it
is the same size as chtype (used by addch(3X)). It holds the
common video attributes (such as bold, reverse), as well as a few
bits for color. Those bits correspond to the A_COLOR symbol. The
COLOR_PAIR macro provides a value which can be logically “or”-ed
into the attribute parameter. For example, as long as that value
fits into the A_COLOR mask, then these calls produce similar
results:
attrset(A_BOLD | COLOR_PAIR(pair));
attr_set(A_BOLD, pair, NULL);
However, if the value does not fit, then the COLOR_PAIR macro uses
only the bits that fit. For example, because in ncurses A_COLOR
has eight (8) bits, then COLOR_PAIR(259) is 4 (i.e., 259 is 4 more
than the limit 255).
The PAIR_NUMBER macro extracts a pair number from an int (or
chtype). For example, the input and output values in these
statements would be the same:
int value = A_BOLD | COLOR_PAIR(input);
int output = PAIR_NUMBER(value);
The attrset routine is a legacy feature predating SVr4 curses but
kept in X/Open Curses for the same reason that SVr4 curses kept
it: compatibility.
The remaining attr* functions operate exactly like the
corresponding attr_* functions, except that they take arguments of
type int rather than attr_t.
There is no corresponding attrget function as such in X/Open
Curses, although ncurses provides getattrs (see curs_legacy(3X)).
Change Character Rendition
The routine chgat changes the attributes of a given number of
characters starting at the current cursor location of stdscr. It
does not update the cursor and does not perform wrapping. A
character count of -1 or greater than the remaining window width
means to change attributes all the way to the end of the current
line. The wchgat function generalizes this to any window; the
mvwchgat function does a cursor move before acting.
In these functions, the color pair argument is a color pair index
(as in the first argument of init_pair, see curs_color(3X)).
Change Window Color
The routine color_set sets the current color of the given window
to the foreground/background combination described by the color
pair parameter.
Standout
The routine standout is the same as attron(A_STANDOUT). The
routine standend is the same as attrset(A_NORMAL) or attrset(0),
that is, it turns off all attributes.
X/Open Curses does not mark these “restricted”, because
• they have well established legacy use, and
• there is no ambiguity about the way the attributes might be
combined with a color pair.
Video Attributes
The following video attributes, defined in curses.h, can be passed
to attron, attroff, attrset, and logically “or”-ed with characters
passed to addch(3X).
Name Description
────────────────────────────────────────────────────────────
A_NORMAL Normal display (no highlight)
A_STANDOUT Best highlighting mode available
A_UNDERLINE Underlining
A_REVERSE Reverse video
A_BLINK Blinking
A_DIM Half bright
A_BOLD Extra bright or bold
A_PROTECT Protected mode
A_INVIS Invisible or blank mode
A_ALTCHARSET Alternate character set
A_ITALIC Italics (non-X/Open extension)
A_ATTRIBUTES Mask to extract character code
A_CHARTEXT Mask to extract attributes
A_COLOR Mask to extract color pair identifier
attr_on, attr_off, and attr_set support the foregoing as well as
the following additional attributes.
Name Description
────────────────────────────────────────────────────────────
WA_HORIZONTAL Horizontal highlight
WA_LEFT Left highlight
WA_LOW Low highlight
WA_RIGHT Right highlight
WA_TOP Top highlight
WA_VERTICAL Vertical highlight
These functions return OK on success and ERR on failure.
In ncurses, they return ERR if win is NULL.
wcolor_set returns ERR if pair is outside the range
0..COLOR_PAIRS-1.
wattr_get does not fail if its attrs or pair parameter is NULL.
Functions prefixed with “mv” first perform cursor movement and
fail if the position (y, x) is outside the window boundaries.
attr_on, attr_off, attr_set, wattr_set, chgat, mvchgat, mvwchgat,
wchgat, and color_set are part of ncurses's wide-character API,
and are not available in its non-wide-character configuration.
attron, wattron, attroff, wattroff, attrset, wattrset, standout,
and standend may be implemented as macros.
Color pair values may be logically “or”-ed with attributes if the
pair number is less than 256. The alternate functions such as
color_set can pass a color pair value directly. However, ncurses
ABI 4 and 5 simply logically “or” this value within the alternate
functions. You must use ncurses ABI 6 to support more than 256
color pairs.
This implementation provides the A_ITALIC attribute for terminals
which have the enter_italics_mode (sitm) and exit_italics_mode
(ritm) capabilities. Italics are not mentioned in X/Open Curses.
Unlike the other video attributes, A_ITALIC is unrelated to the
set_attributes capabilities. This implementation makes the
assumption that exit_attribute_mode may also reset italics.
Each of the functions added by XSI Curses has a parameter opts,
which X/Open Curses still (after more than twenty years) documents
as reserved for future use, saying that it should be NULL. This
implementation uses that parameter in ABI 6 for the functions
which have a color pair parameter to support extended color pairs:
• For functions which modify the color, e.g., wattr_set and
wattr_on, if opts is set it is treated as a pointer to int,
and used to set the color pair instead of the short pair
parameter.
• For functions which retrieve the color, e.g., wattr_get, if
opts is set it is treated as a pointer to int, and used to
retrieve the color pair as an int value, in addition to
retrieving it via the standard pointer to short parameter.
• For functions which turn attributes off, e.g., wattr_off, the
opts parameter is ignored except to check that it is NULL.
These functions are described in X/Open Curses Issue 4. It
specifies no error conditions for them.
The standard defined the dedicated type for highlights, attr_t,
which was not defined in SVr4 curses. The functions taking attr_t
arguments were not supported under SVr4.
SVr4 describes the functions not taking attr_t or pair arguments
as always returning 1.
Very old versions of this library did not force an update of the
screen when changing the attributes. Use touchwin to force the
screen to match the updated attributes.
X/Open Curses states that whether the traditional functions
attron/attroff/attrset can manipulate attributes other than
A_BLINK, A_BOLD, A_DIM, A_REVERSE, A_STANDOUT, or A_UNDERLINE is
“unspecified”. Under this implementation as well as SVr4 curses,
these functions correctly manipulate all other highlights
(specifically, A_ALTCHARSET, A_PROTECT, and A_INVIS).
X/Open Curses added these entry points:
attr_get, attr_on, attr_off, attr_set, wattr_on, wattr_off,
wattr_get, wattr_set
The new functions are intended to work with a new series of
highlight macros prefixed with WA_. The older macros have direct
counterparts in the newer set of names:
Name Description
─────────────────────────────────────────────────
WA_NORMAL Normal display (no highlight)
WA_STANDOUT Best highlighting mode available
WA_UNDERLINE Underlining
WA_REVERSE Reverse video
WA_BLINK Blinking
WA_DIM Half bright
WA_BOLD Extra bright or bold
WA_ALTCHARSET Alternate character set
X/Open Curses does not assign values to these symbols, nor does it
state whether or not they are related to the similarly-named
A_NORMAL, etc.:
• X/Open Curses specifies that each pair of corresponding A_ and
WA_-using functions operates on the same current-highlight
information.
• However, in some implementations, those symbols have unrelated
values.
For example, the Solaris xpg4 (X/Open) curses declares attr_t
to be an unsigned short integer (16-bits), while chtype is a
unsigned integer (32-bits). The WA_ symbols in this case are
different from the A_ symbols because they are used for a
smaller datatype which does not represent A_CHARTEXT or
A_COLOR.
In this implementation (as in many others), the values happen
to be the same because it simplifies copying information
between chtype and cchar_t variables.
• Because ncurses's attr_t can hold a color pair (in the A_COLOR
field), a call to wattr_on, wattr_off, or wattr_set may alter
the window's color. If the color pair information in the
attribute parameter is zero, no change is made to the window's
color.
This is consistent with SVr4 curses; X/Open Curses does not
specify this.
The X/Open Curses extended conformance level adds new highlights
A_HORIZONTAL, A_LEFT, A_LOW, A_RIGHT, A_TOP, A_VERTICAL (and
corresponding WA_ macros for each). As of August 2013, no known
terminal provides these highlights (i.e., via the sgr1
capability).
4BSD (1980) used a char to represent each cell of the terminal
screen. It assumed 7-bit character codes, employing the eighth
bit of a byte to represent a standout attribute (often implemented
as bold and/or reverse video). It introduced standout, standend,
wstandout, and wstandend functions to manipulate this bit.
Despite their inflexibility, they carried over into System V
curses and ultimately X/Open Curses due to their pervasive use in
legacy applications. While some 1980s terminals supported a
variety of video attributes, BSD curses could do nothing with
them.
SVr2 (1984) provided an improved curses library, introducing
chtype to create the abstract notion of a curses character; this
was by default an unsigned short, with a provision for compile-
time redefinition to other integral types (a freedom not
necessarily available to users of shared libraries, and in any
event a source license was necessary to exercise it). It added
the functions attron, attroff, attrset, wattron, wattroff, and
wattrset, and defined the A_ macros listed above (except for
A_ITALIC and A_COLOR) for use by applications to manipulate other
attributes. The values of these macros were not necessarily the
same in different systems, even among those certified as System V.
SVr3.2 (1988) added the A_COLOR macro along with a color system;
see curs_color(3X).
X/Open Curses Issue 4 (1995) is largely based on SVr4 curses, but
recognized that the wchar_t type of ISO C95 was intended to house
only a single character code, not a sequence of codes combining
with a base character, let alone could it reliably offer room for
a color pair identifier and a set of attribute bits with a
potential for further growth — thus the standard invented the
curses complex character type cchar_t and a separate type attr_t
for storage of attribute bits. The new types brought along
several new functions to manipulate them, some corresponding to
existing chtype-based functions (attr_on, attr_off, attr_set,
wattr_on, wattr_off, and wattr_set), and some new (chgat and its
variants, color_set, and wcolor_set).
Different Unix systems used differently sized bit fields in chtype
for the character code and the color pair identifier, and took
into account platforms' different integer sizes (32- versus
64-bit).
The following table showing the number of bits for A_COLOR and
A_CHARTEXT was gleaned from the curses header files for various
operating systems and architectures. The inferred architecture
and notes reflect the format and size of the defined constants as
well as clues such as the alternate character set implementation.
A 32-bit library can be used on a 64-bit system, but not
necessarily the converse.
Bits
Year System Arch Color Char Notes
───────────────────────────────────────────────────────────────────
1992 Solaris 5.2 32 6 17 SVr4 curses
1992 HP-UX 9 32 no 8 SVr2 curses
1992 AIX 3.2 32 no 23 SVr2 curses
1994 OSF/1 r3 32 no 23 SVr2 curses
1995 HP-UX 10.00 32 6 16 SVr3 curses_colr
1995 HP-UX 10.00 32 6 8 SVr4, X/Open curses
1995 Solaris 5.4 32/64 7 16 X/Open curses
1996 AIX 4.2 32 7 16 X/Open curses
1996 OSF/1 r4 32 6 16 X/Open curses
1997 HP-UX 11.00 32 6 8 X/Open curses
2000 UWIN 32/64 7/31 16 uses chtype
Notes:
Regarding HP-UX,
• HP-UX 10.20 (1996) added support for 64-bit PA-RISC
processors in 1996.
• HP-UX 10.30 (1997) marked “curses_colr” obsolete. That
version of curses was dropped with HP-UX 11.30 in 2006.
Regarding OSF/1 (and Tru64),
• These used 64-bit hardware. Like ncurses, the OSF/1 curses
interface is not customized for 32-bit and 64-bit versions.
• Unlike other systems which evolved from AT&T code, OSF/1
provided a new implementation for X/Open Curses.
Regarding Solaris,
• The initial release of Solaris was in 1992.
• Its XPG4 (X/Open Curses-conforming) xcurses library was
developed by Mortice Kern Systems from 1990 to 1995. Sun's
copyright began in 1996.
• Sun updated the X/Open Curses interface after 64-bit
support was introduced in 1997, but did not modify the SVr4
curses interface.
Regarding UWIN,
• Development of the curses library began in 1991, stopped in
2000.
• Color support was added in 1998.
• The library uses only chtype (not cchar_t).
Once X/Open Curses was adopted in the mid-1990s, the constraint of
a 32-bit interface with many colors and wide-characters for chtype
became a moot point. The cchar_t structure (whose size and
members are not specified in X/Open Curses) could be extended as
needed.
Other interfaces are rarely used now.
• BSD curses was improved slightly in 1993/1994 using Keith
Bostic's modification to make the library 8-bit clean for
nvi(1). He moved the standout attribute to a structure
member. The resulting 4.4BSD curses was replaced by ncurses
over the next ten years.
• UWIN has been defunct since 2012.
ncurses 6.0 (2015) added the A_ITALIC macro.
curses(3X), curs_addch(3X), curs_addstr(3X), curs_bkgd(3X),
curs_printw(3X), curs_variables(3X)
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://invisible-island.net/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to bug-ncurses@gnu.org.
This page was obtained from the tarball ncurses-6.6.tar.gz fetched
from ⟨https://ftp.gnu.org/gnu/ncurses/⟩ on 2026-01-16. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for the
page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
ncurses @NCURSES_MAJOR@.@NCU... 2025-11-11 curs_attr(3X)
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HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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