curs_variables(3X)                                          curs_variables(3X)

NAME
       COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE, curscr, newscr,
       stdscr - curses global variables

SYNOPSIS
       #include <curses.h>

       int COLOR_PAIRS;
       int COLORS;
       int COLS;
       int ESCDELAY;
       int LINES;
       int TABSIZE;
       WINDOW * curscr;
       WINDOW * newscr;
       WINDOW * stdscr;

DESCRIPTION
       This page summarizes variables provided by the curses library.  A more
       complete description is given in the curses(3X) manual page.

       Depending on the configuration, these may be actual variables, or
       macros (see curs_threads(3X) and curs_opaque(3X)) which provide read-
       only access to curses's state.  In either case, applications should
       treat them as read-only to avoid confusing the library.

   COLOR_PAIRS
       After initializing curses, this variable contains the number of color
       pairs which the terminal can support.  Usually the number of color
       pairs will be the product COLORS*COLORS, however this is not always
       true:

       • a few terminals use HLS colors, which do not follow this rule

       • terminals supporting a large number of colors are limited by the
           number of color pairs that can be represented in a signed short
           value.

   COLORS
       After initializing curses, this variable contains the number of colors
       which the terminal can support.

   COLS
       After initializing curses, this variable contains the width of the
       screen, i.e., the number of columns.

   ESCDELAY
       This variable holds the number of milliseconds to wait after reading an
       escape character, to distinguish between an individual escape character
       entered on the keyboard from escape sequences sent by cursor- and
       function-keys (see curses(3X)).

   LINES
       After initializing curses, this variable contains the height of the
       screen, i.e., the number of lines.

   TABSIZE
       This variable holds the number of columns used by the curses library
       when converting a tab character to spaces as it adds the tab to a
       window (see curs_addch(3X).

   The Current Screen
       This implementation of curses uses a special window curscr to record
       its updates to the terminal screen.

       This is referred to as the "physical screen" in the curs_refresh(3X)
       and curs_outopts(3X) manual pages.

   The New Screen
       This implementation of curses uses a special window newscr to hold
       updates to the terminal screen before applying them to curscr.

       This is referred to as the "virtual screen" in the curs_kernel(3X),
       curs_refresh(3X) and curs_outopts(3X) manual pages.

   The Standard Screen
       Upon initializing curses, a default window called stdscr, which is the
       size of the terminal screen, is created.  Many curses functions use
       this window.

NOTES
       The curses library is initialized using either initscr(3X), or
       newterm(3X).

       If curses is configured to use separate curses/terminfo libraries, most
       of these variables reside in the curses library.

PORTABILITY
       TABSIZE is a feature of SVr4 curses which is not documented by X/Open
       curses.

       • In SVr4 curses, TABSIZE is initially set from the terminal
           description's init_tabs capability.  After that, it can be altered
           by the applications using SVr4 curses.

           SVr4 curses uses the current value of TABSIZE to compute the
           position of tabstops for updating both the virtual screen with
           addch(3X) as well as the physical screen with mvcur(3X).

       • This implementation uses the current value of TABSIZE only for
           updating the virtual screen.  It uses the terminal description's it
           (init_tabs) capability for computing hardware tabs (i.e., tab stops
           on the physical screen).

       • Other implementations differ.  For instance, NetBSD curses allows
           TABSIZE to be set through an environment variable.  This
           implementation does not.

           NetBSD curses does not support hardware tabs; it uses the init_tabs
           capability and the TABSIZE variable only for updating the virtual
           screen.

       ESCDELAY is an extension in AIX curses:

       • In AIX, the units for ESCDELAY are fifths of a millisecond.

       • The default value for AIX's ESCDELAY is 0.1 seconds.

       • AIX also enforces a limit of 10,000 seconds for ESCDELAY; this
           implementation currently has no upper limit.

       This implementation has long used ESCDELAY with units of milliseconds,
       making it impossible to be completely compatible with AIX.  Likewise,
       most users have either decided to override the value, or rely upon its
       default value.

SEE ALSO
       curses(3X), curs_opaque(3X), curs_terminfo(3X), curs_threads(3X),
       term_variables(3X), terminfo(5).

                                                            curs_variables(3X)