# curs_variables 3x

    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:

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

           o   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 func-
           tion-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  win-
           dow (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 up-
           dates 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.

           o   In SVr4 curses, TABSIZE is initially set from the terminal descrip-
               tion'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  posi-
               tion  of  tabstops  for  updating both the virtual screen with add-
               ch(3x) as well as the physical screen with mvcur(3x).

           o   This implementation uses the current value of TABSIZE only for  up-
               dating  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).

           o   Other  implementations  differ.  For instance, NetBSD curses allows
               TABSIZE to be set through an environment variable.  This  implemen-
               tation 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:

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

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

           o   AIX  also enforces a limit of 10,000 seconds for ESCDELAY; this im-
               plementation 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)