curs_color, start_color, init_pair, init_color, has_colors,
can_change_color, color_content, pair_content, COLOR_PAIR, COLOR_PAIRS,
COLORS, PAIR_NUMBER - Curses color-manipulation routines and variables
# include <curses.h>
void ); int init_pair(
short b ); int init_color(
short b ); bool has_colors(
void ); bool can_change_color(
void ); int color_content(
short *b ); int pair_content(
short *b ); int COLOR_PAIR(
int n ); int PAIR_NUMBER(
int value );
Curses Library (libcurses)
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
start_color, init_pair, init_color, has_colors, can_change_color,
color_content, pair_content, COLOR_PAIR, PAIR_NUMBER: XCURSES4.2
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
The Curses library includes routines that manipulate color-on-color
alphanumeric terminals. To use these routines, applications must call
start_color, usually right after initscr. Colors are always used in
pairs (referred to as color-pairs). A color-pair consists of a fore‐
ground color (for characters) and a background color (for the field on
which the characters are displayed). An application calls init_pair to
initialize a color-pair. After the color-pair is initialized, applica‐
tions can call COLOR_PAIR(n) to use color attributes.
If a terminal is capable of redefining colors, applications can use the
routine init_color to change the definition of a color. The routines
has_colors and can_change_color return TRUE or FALSE, depending on
whether the terminal has color capabilities and whether the application
can change the colors. The routine color_content allows an application
to identify the amounts of red, green, and blue components in an ini‐
tialized color. The routine pair_content allows the application to find
out how a given color-pair is currently defined.
The start_color routine requires no arguments. It must be called if the
application uses colors, and before the application calls any other
color manipulation routine. It is good practice to call this routine
right after initscr. The start_color routine initializes eight basic
colors (black, red, green, yellow, blue, magenta, cyan, and white) and
two global variables (COLORS and COLOR_PAIRS, which respectively define
the maximum number of colors and color-pairs the terminal can support).
The start_color routine also restores the colors on the terminal to the
values they had when the terminal was turned on.
The init_pair routine changes the definition of a color-pair. This rou‐
tine takes three arguments that are identification numbers for the fol‐
lowing: The color-pair to be changed The foreground color The back‐
The value of the first argument must be between 1 and the smaller of
either 63 or COLOR_PAIRS-1. The values of the second and third argu‐
ments must be between 0 and COLORS. If the color-pair was previously
initialized, the screen is refreshed and all occurrences of that color-
pair are changed to the new definition.
The init_color routine changes the definition of a color. This routine
takes four arguments: the number of the color to be changed followed by
three RGB values (for the amounts of red, green, and blue components,
respectively). The value of the first argument must be between 0 and
COLORS. (See the subsection Colors for the default color index.) Each
of the last three arguments must be a value between 0 and 1000. When
init_color is used, all occurrences of that color on the screen immedi‐
ately change to the new definition.
The has_colors routine requires no arguments. It returns TRUE if the
terminal can manipulate colors; otherwise, the routine returns FALSE.
This routine facilitates writing terminal-independent programs. For
example, a programmer can use it to decide whether to use color or some
other video attribute.
The can_change_color routine requires no arguments. It returns TRUE if
the terminal supports colors and can change their definitions; other‐
wise, the routine returns FALSE. This routine facilitates writing ter‐
The color_content routine gives users a way to find the intensity of
the red, green, and blue (RGB) components in a color. This routine
requires four arguments: the color number, and three addresses (of
short data type) for storing the information about the amounts of red,
green, and blue components in the given color. The value of the first
argument must be between 0 and COLORS. The values that are stored at
the addresses pointed to by the last three arguments are between 0 (no
component) and 1000 (maximum amount of component).
The pair_content routine allows users to find out which colors a given
color-pair consists of. This routine requires three arguments: the
color-pair number, and two addresses (of short data type) for storing
the numbers for the foreground and background colors. The value of the
first argument must be between 1 and the smaller of 63 or
COLOR_PAIRS-1. The values that are stored at the addresses pointed to
by the second and third arguments are between 0 and COLORS.
The COLOR_PAIR(n) macro returns the value of the color-pair whose num‐
ber is n. This value is the color attribute as it would be extracted
from a chtype variable. Conversely, the macro PAIR_NUMBER(value)
returns the number of the color-pair associated with the color
In <curses.h>, the following macros are defined. These are the default
colors. Curses also assumes that COLOR_BLACK is the default background
color for all terminals.
COLOR_BLACK COLOR_RED COLOR_GREEN COLOR_YELLOW COLOR_BLUE COLOR_MAGENTA
The header file <curses.h> automatically includes the header file
Note that COLOR_PAIR and PAIR_NUMBER may be macros.
The COLOR_PAIR, PAIR_NUMBER, can_change_color, and has_colors routines
return values as indicated in the DESCRIPTION section.
All other routines return ERR upon failure and OK upon successful com‐
Functions: curses(3), curs_attr_get(3), curs_initscr(3)