1curs_variables(3X)                                          curs_variables(3X)
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NAME

6       COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE, curscr, newscr,
7       stdscr - curses global variables
8

SYNOPSIS

10       #include <curses.h>
11
12       int COLOR_PAIRS;
13       int COLORS;
14       int COLS;
15       int ESCDELAY;
16       int LINES;
17       int TABSIZE;
18       WINDOW * curscr;
19       WINDOW * newscr;
20       WINDOW * stdscr;
21

DESCRIPTION

23       This page summarizes variables provided by the curses library.  A  more
24       complete description is given in the curses(3X) manual page.
25
26       Depending  on  the  configuration,  these  may  be actual variables, or
27       macros (see curs_threads(3X) and curs_opaque(3X)) which  provide  read-
28       only  access  to  curses's  state.  In either case, applications should
29       treat them as read-only to avoid confusing the library.
30
31   COLOR_PAIRS
32       After initializing curses, this variable contains the number  of  color
33       pairs  which  the  terminal  can  support.  Usually the number of color
34       pairs will be the product COLORS*COLORS, however  this  is  not  always
35       true:
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37       •   a few terminals use HLS colors, which do not follow this rule
38
39       •   terminals  supporting  a  large number of colors are limited by the
40           number of color pairs that can be represented  in  a  signed  short
41           value.
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43   COLORS
44       After  initializing curses, this variable contains the number of colors
45       which the terminal can support.
46
47   COLS
48       After initializing curses, this variable  contains  the  width  of  the
49       screen, i.e., the number of columns.
50
51   ESCDELAY
52       This variable holds the number of milliseconds to wait after reading an
53       escape character, to distinguish between an individual escape character
54       entered on the keyboard from escape sequences sent by cursor- and func‐
55       tion-keys (see curses(3X)).
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57   LINES
58       After initializing curses, this variable contains  the  height  of  the
59       screen, i.e., the number of lines.
60
61   TABSIZE
62       This  variable  holds  the number of columns used by the curses library
63       when converting a tab character to spaces as it adds the tab to a  win‐
64       dow (see curs_addch(3X).
65
66   The Current Screen
67       This  implementation  of  curses uses a special window curscr to record
68       its updates to the terminal screen.
69
70       This is referred to as the “physical screen”  in  the  curs_refresh(3X)
71       and curs_outopts(3X) manual pages.
72
73   The New Screen
74       This  implementation of curses uses a special window newscr to hold up‐
75       dates to the terminal screen before applying them to curscr.
76
77       This is referred to as the “virtual  screen”  in  the  curs_kernel(3X),
78       curs_refresh(3X) and curs_outopts(3X) manual pages.
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80   The Standard Screen
81       Upon  initializing curses, a default window called stdscr, which is the
82       size of the terminal screen, is created.   Many  curses  functions  use
83       this window.
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NOTES

86       The   curses  library  is  initialized  using  either  initscr(3X),  or
87       newterm(3X).
88
89       If curses is configured to use separate curses/terminfo libraries, most
90       of these variables reside in the curses library.
91

PORTABILITY

93       TABSIZE  is  a feature of SVr4 curses which is not documented by X/Open
94       curses.
95
96       •   In SVr4 curses, TABSIZE is initially set from the terminal descrip‐
97           tion's  init_tabs capability.  After that, it can be altered by the
98           applications using SVr4 curses.
99
100           SVr4 curses uses the current value of TABSIZE to compute the  posi‐
101           tion  of  tabstops  for  updating both the virtual screen with add‐
102           ch(3X) as well as the physical screen with mvcur(3X).
103
104       •   This implementation uses the current value of TABSIZE only for  up‐
105           dating  the  virtual screen.  It uses the terminal description's it
106           (init_tabs) capability for computing hardware tabs (i.e., tab stops
107           on the physical screen).
108
109       •   Other  implementations  differ.  For instance, NetBSD curses allows
110           TABSIZE to be set through an environment variable.  This  implemen‐
111           tation does not.
112
113           NetBSD curses does not support hardware tabs; it uses the init_tabs
114           capability and the TABSIZE variable only for updating  the  virtual
115           screen.
116
117       ESCDELAY is an extension in AIX curses:
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119       •   In AIX, the units for ESCDELAY are fifths of a millisecond.
120
121       •   The default value for AIX's ESCDELAY is 0.1 seconds.
122
123       •   AIX  also enforces a limit of 10,000 seconds for ESCDELAY; this im‐
124           plementation currently has no upper limit.
125
126       This implementation has long used ESCDELAY with units of  milliseconds,
127       making  it  impossible to be completely compatible with AIX.  Likewise,
128       most users have either decided to override the value, or rely upon  its
129       default value.
130

SEE ALSO

132       curses(3X),   curs_opaque(3X),   curs_terminfo(3X),   curs_threads(3X),
133       term_variables(3X), terminfo(5).
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137                                                            curs_variables(3X)
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