# ncurses 3x

    ncurses(3x)                                                        ncurses(3x)

## NAME

           ncurses - CRT screen handling and optimization package

## SYNOPSIS

           #include <curses.h>

## DESCRIPTION

           The  ncurses  library  routines  give  the  user a terminal-independent
           method of updating  character  screens  with  reasonable  optimization.
           This  implementation  is  "new  curses"  (ncurses)  and is the approved
           replacement for 4.4BSD classic curses,  which  has  been  discontinued.
           This describes ncurses version 6.3 (patch 20211021).

           The  ncurses  library emulates the curses library of System V Release 4
           UNIX, and XPG4 (X/Open Portability Guide) curses  (also  known  as  XSI
           curses).   XSI  stands  for  X/Open  System  Interfaces Extension.  The
           ncurses library is freely redistributable in source form.   Differences
           from   the   SVr4  curses  are  summarized  under  the  EXTENSIONS  and
           PORTABILITY sections below and described in detail  in  the  respective
           EXTENSIONS, PORTABILITY and BUGS sections of individual man pages.

           The  ncurses  library  also  provides  many  useful  extensions,  i.e.,
           features which cannot be implemented by a  simple  add-on  library  but
           which require access to the internals of the library.

           A  program  using  these  routines  must  be  linked with the -lncurses
           option, or (if it  has  been  generated)  with  the  debugging  library
           -lncurses_g.   (Your  system  integrator  may also have installed these
           libraries under the names  -lcurses  and  -lcurses_g.)   The  ncurses_g
           library  generates  trace logs (in a file called "trace" in the current
           directory) that describe curses  actions.   See  also  the  section  on
           ALTERNATE CONFIGURATIONS.

           The   ncurses   package   supports:  overall  screen,  window  and  pad
           manipulation; output to  windows  and  pads;  reading  terminal  input;
           control  over terminal and curses input and output options; environment
           query routines; color manipulation; use of soft  label  keys;  terminfo
           capabilities; and access to low-level terminal-manipulation routines.

### Initialization

           The  library uses the locale which the calling program has initialized.
           That is normally done with setlocale:

               setlocale(LC_ALL, "");

           If the locale is not initialized, the library assumes  that  characters
           are  printable  as in ISO-8859-1, to work with certain legacy programs.
           You should initialize the locale and not rely on  specific  details  of
           the library when the locale has not been setup.

           The  function  initscr  or  newterm  must  be  called to initialize the
           library before any of the other routines that  deal  with  windows  and
           screens  are  used.   The  routine  endwin(3x)  must  be  called before
           exiting.

           To get character-at-a-time input  without  echoing  (most  interactive,
           screen  oriented  programs want this), the following sequence should be
           used:

               initscr(); cbreak(); noecho();

           Most programs would additionally use the sequence:

               intrflush(stdscr, FALSE);
               keypad(stdscr, TRUE);

           Before a curses program is run, the tab stops of the terminal should be
           set  and  its initialization strings, if defined, must be output.  This
           can be done  by  executing  the  tput  init  command  after  the  shell
           environment  variable  TERM  has  been  exported.   tset(1)  is usually
           responsible for doing this.  [See terminfo(5) for further details.]

### Datatypes

           The ncurses library permits manipulation  of  data  structures,  called
           windows,   which  can  be  thought  of  as  two-dimensional  arrays  of
           characters representing all or part of a CRT screen.  A default  window
           called  stdscr,  which is the size of the terminal screen, is supplied.
           Others may be created with newwin.

           Note that curses does not handle overlapping windows,  that's  done  by
           the  panel(3x)  library.   This means that you can either use stdscr or
           divide the screen into tiled windows  and  not  using  stdscr  at  all.
           Mixing the two will result in unpredictable, and undesired, effects.

           Windows  are referred to by variables declared as WINDOW *.  These data
           structures are manipulated with routines described here  and  elsewhere
           in  the ncurses manual pages.  Among those, the most basic routines are
           move and addch.  More general versions of these routines  are  included
           with  names  beginning  with  w, allowing the user to specify a window.
           The routines not beginning with w affect stdscr.

           After using routines to manipulate a  window,  refresh(3x)  is  called,
           telling  curses  to  make  the user's CRT screen look like stdscr.  The
           characters in a window are actually  of  type  chtype,  (character  and
           attribute  data) so that other information about the character may also
           be stored with each character.

           Special windows called pads may also be manipulated.  These are windows
           which  are not constrained to the size of the screen and whose contents
           need  not  be  completely  displayed.   See   curs_pad(3x)   for   more
           information.

           In  addition  to drawing characters on the screen, video attributes and
           colors may be supported, causing the characters  to  show  up  in  such
           modes  as  underlined,  in reverse video, or in color on terminals that
           support such display enhancements.   Line  drawing  characters  may  be
           specified  to  be  output.   On input, curses is also able to translate
           arrow and function keys that  transmit  escape  sequences  into  single
           values.   The  video  attributes,  line  drawing  characters, and input
           values use names, defined in <curses.h>, such as A_REVERSE,  ACS_HLINE,
           and KEY_LEFT.

### Environment variables

           If  the  environment  variables  LINES  and  COLUMNS are set, or if the
           program  is  executing  in  a  window  environment,  line  and   column
           information  in  the  environment  will  override  information  read by
           terminfo.  This would affect a program running in an  AT&T  630  layer,
           for   example,   where   the  size  of  a  screen  is  changeable  (see
           ENVIRONMENT).

           If the environment variable TERMINFO  is  defined,  any  program  using
           curses  checks  for  a local terminal definition before checking in the
           standard place.  For example, if TERM  is  set  to  att4424,  then  the
           compiled terminal definition is found in

               /usr/share/terminfo/a/att4424.

           (The  a is copied from the first letter of att4424 to avoid creation of
           huge directories.)  However,  if  TERMINFO  is  set  to  $HOME/myterms,
           curses first checks

               $HOME/myterms/a/att4424,

           and if that fails, it then checks

               /usr/share/terminfo/a/att4424.

           This  is  useful  for developing experimental definitions or when write
           permission in /usr/share/terminfo is not available.

           The integer variables LINES and COLS are defined in <curses.h> and will
           be  filled  in  by  initscr with the size of the screen.  The constants
           TRUE and FALSE have the values 1 and 0, respectively.

           The curses routines also define the WINDOW * variable curscr  which  is
           used  for  certain  low-level  operations like clearing and redrawing a
           screen containing garbage.  The curscr  can  be  used  in  only  a  few
           routines.

### Routine and Argument Names

           Many  curses routines have two or more versions.  The routines prefixed
           with w require a window argument.  The routines prefixed with p require
           a pad argument.  Those without a prefix generally use stdscr.

           The  routines  prefixed with mv require a y and x coordinate to move to
           before performing the appropriate action.  The mv routines imply a call
           to  move before the call to the other routine.  The coordinate y always
           refers to the row (of the window), and x always refers to  the  column.
           The upper left-hand corner is always (0,0), not (1,1).

           The  routines prefixed with mvw take both a window argument and x and y
           coordinates.  The  window  argument  is  always  specified  before  the
           coordinates.

           In  each case, win is the window affected, and pad is the pad affected;
           win and pad are always pointers to type WINDOW.

           Option setting routines require a Boolean flag bf with the  value  TRUE
           or  FALSE;  bf  is always of type bool.  Most of the data types used in
           the library routines, such as WINDOW,  SCREEN,  bool,  and  chtype  are
           defined  in  <curses.h>.   Types used for the terminfo routines such as
           TERMINAL are defined in <term.h>.

           This  manual  page  describes  functions  which  may  appear   in   any
           configuration  of  the library.  There are two common configurations of
           the library:

              ncurses
                   the "normal" library,  which  handles  8-bit  characters.   The
                   normal   (8-bit)   library   stores  characters  combined  with
                   attributes in chtype data.

                   Attributes alone (no corresponding character) may be stored  in
                   chtype or the equivalent attr_t data.  In either case, the data
                   is stored in something like an integer.

                   Each cell (row and column) in a WINDOW is stored as a chtype.

              ncursesw
                   the  so-called  "wide"   library,   which   handles   multibyte
                   characters  (see the section on ALTERNATE CONFIGURATIONS).  The
                   "wide" library includes all of  the  calls  from  the  "normal"
                   library.   It  adds about one third more calls using data types
                   which store multibyte characters:

                   cchar_t
                        corresponds to chtype.  However it is a structure, because
                        more  data  is  stored  than can fit into an integer.  The
                        characters are large enough  to  require  a  full  integer
                        value - and there may be more than one character per cell.
                        The video attributes and  color  are  stored  in  separate
                        fields of the structure.

                        Each  cell  (row  and  column)  in a WINDOW is stored as a
                        cchar_t.

                        The setcchar(3x)  and  getcchar(3x)  functions  store  and
                        retrieve the data from a cchar_t structure.

                   wchar_t
                        stores  a  "wide"  character.  Like chtype, this may be an
                        integer.

                   wint_t
                        stores a wchar_t or WEOF - not the same, though  both  may
                        have the same size.

                   The  "wide"  library provides new functions which are analogous
                   to functions in  the  "normal"  library.   There  is  a  naming
                   convention  which  relates  many of the normal/wide variants: a
                   "_w" is inserted into the name.  For  example,  waddch  becomes
                   wadd_wch.

### Routine Name Index

           The  following table lists the curses routines provided in the "normal"
           and "wide" libraries and the names of the manual pages  on  which  they
           are  described.   Routines  flagged  with "*" are ncurses-specific, not
           described by XPG4 or present in SVr4.

                        curses Routine Name      Manual Page Name
                        ---------------------------------------------
                        COLOR_PAIR               curs_color(3x)
                        PAIR_NUMBER              curs_attr(3x)
                        add_wch                  curs_add_wch(3x)
                        add_wchnstr              curs_add_wchstr(3x)
                        add_wchstr               curs_add_wchstr(3x)
                        addch                    curs_addch(3x)
                        addchnstr                curs_addchstr(3x)
                        addchstr                 curs_addchstr(3x)
                        addnstr                  curs_addstr(3x)
                        addnwstr                 curs_addwstr(3x)
                        addstr                   curs_addstr(3x)
                        addwstr                  curs_addwstr(3x)
                        alloc_pair               new_pair(3x)*
                        assume_default_colors    default_colors(3x)*
                        attr_get                 curs_attr(3x)
                        attr_off                 curs_attr(3x)
                        attr_on                  curs_attr(3x)
                        attr_set                 curs_attr(3x)
                        attroff                  curs_attr(3x)
                        attron                   curs_attr(3x)
                        attrset                  curs_attr(3x)
                        baudrate                 curs_termattrs(3x)
                        beep                     curs_beep(3x)
                        bkgd                     curs_bkgd(3x)
                        bkgdset                  curs_bkgd(3x)
                        bkgrnd                   curs_bkgrnd(3x)
                        bkgrndset                curs_bkgrnd(3x)
                        border                   curs_border(3x)

                        border_set               curs_border_set(3x)
                        box                      curs_border(3x)
                        box_set                  curs_border_set(3x)
                        can_change_color         curs_color(3x)
                        cbreak                   curs_inopts(3x)
                        chgat                    curs_attr(3x)
                        clear                    curs_clear(3x)
                        clearok                  curs_outopts(3x)
                        clrtobot                 curs_clear(3x)
                        clrtoeol                 curs_clear(3x)
                        color_content            curs_color(3x)
                        color_set                curs_attr(3x)
                        copywin                  curs_overlay(3x)
                        curs_set                 curs_kernel(3x)
                        curses_trace             curs_trace(3x)*
                        curses_version           curs_extend(3x)*
                        def_prog_mode            curs_kernel(3x)
                        def_shell_mode           curs_kernel(3x)
                        define_key               define_key(3x)*
                        del_curterm              curs_terminfo(3x)
                        delay_output             curs_util(3x)
                        delch                    curs_delch(3x)
                        deleteln                 curs_deleteln(3x)
                        delscreen                curs_initscr(3x)
                        delwin                   curs_window(3x)
                        derwin                   curs_window(3x)
                        doupdate                 curs_refresh(3x)
                        dupwin                   curs_window(3x)
                        echo                     curs_inopts(3x)
                        echo_wchar               curs_add_wch(3x)
                        echochar                 curs_addch(3x)
                        endwin                   curs_initscr(3x)
                        erase                    curs_clear(3x)
                        erasechar                curs_termattrs(3x)
                        erasewchar               curs_termattrs(3x)
                        exit_curses              curs_memleaks(3x)*
                        exit_terminfo            curs_memleaks(3x)*
                        extended_color_content   curs_color(3x)*
                        extended_pair_content    curs_color(3x)*
                        extended_slk_color       curs_slk(3x)*
                        filter                   curs_util(3x)
                        find_pair                new_pair(3x)*
                        flash                    curs_beep(3x)
                        flushinp                 curs_util(3x)
                        free_pair                new_pair(3x)*
                        get_wch                  curs_get_wch(3x)
                        get_wstr                 curs_get_wstr(3x)
                        getattrs                 curs_attr(3x)
                        getbegx                  curs_legacy(3x)*
                        getbegy                  curs_legacy(3x)*
                        getbegyx                 curs_getyx(3x)
                        getbkgd                  curs_bkgd(3x)
                        getbkgrnd                curs_bkgrnd(3x)
                        getcchar                 curs_getcchar(3x)
                        getch                    curs_getch(3x)
                        getcurx                  curs_legacy(3x)*
                        getcury                  curs_legacy(3x)*
                        getmaxx                  curs_legacy(3x)*
                        getmaxy                  curs_legacy(3x)*
                        getmaxyx                 curs_getyx(3x)
                        getmouse                 curs_mouse(3x)*
                        getn_wstr                curs_get_wstr(3x)
                        getnstr                  curs_getstr(3x)
                        getparx                  curs_legacy(3x)*
                        getpary                  curs_legacy(3x)*

                        getparyx                 curs_getyx(3x)
                        getstr                   curs_getstr(3x)
                        getsyx                   curs_kernel(3x)
                        getwin                   curs_util(3x)
                        getyx                    curs_getyx(3x)
                        halfdelay                curs_inopts(3x)
                        has_colors               curs_color(3x)
                        has_ic                   curs_termattrs(3x)
                        has_il                   curs_termattrs(3x)
                        has_key                  curs_getch(3x)*
                        has_mouse                curs_mouse(3x)*
                        hline                    curs_border(3x)
                        hline_set                curs_border_set(3x)
                        idcok                    curs_outopts(3x)
                        idlok                    curs_outopts(3x)
                        immedok                  curs_outopts(3x)
                        in_wch                   curs_in_wch(3x)
                        in_wchnstr               curs_in_wchstr(3x)
                        in_wchstr                curs_in_wchstr(3x)
                        inch                     curs_inch(3x)
                        inchnstr                 curs_inchstr(3x)
                        inchstr                  curs_inchstr(3x)
                        init_color               curs_color(3x)
                        init_extended_color      curs_color(3x)*
                        init_extended_pair       curs_color(3x)*
                        init_pair                curs_color(3x)
                        initscr                  curs_initscr(3x)
                        innstr                   curs_instr(3x)
                        innwstr                  curs_inwstr(3x)
                        ins_nwstr                curs_ins_wstr(3x)
                        ins_wch                  curs_ins_wch(3x)
                        ins_wstr                 curs_ins_wstr(3x)
                        insch                    curs_insch(3x)
                        insdelln                 curs_deleteln(3x)
                        insertln                 curs_deleteln(3x)
                        insnstr                  curs_insstr(3x)
                        insstr                   curs_insstr(3x)
                        instr                    curs_instr(3x)
                        intrflush                curs_inopts(3x)
                        inwstr                   curs_inwstr(3x)
                        is_cleared               curs_opaque(3x)*
                        is_idcok                 curs_opaque(3x)*
                        is_idlok                 curs_opaque(3x)*
                        is_immedok               curs_opaque(3x)*
                        is_keypad                curs_opaque(3x)*
                        is_leaveok               curs_opaque(3x)*
                        is_linetouched           curs_touch(3x)
                        is_nodelay               curs_opaque(3x)*
                        is_notimeout             curs_opaque(3x)*
                        is_pad                   curs_opaque(3x)*
                        is_scrollok              curs_opaque(3x)*
                        is_subwin                curs_opaque(3x)*
                        is_syncok                curs_opaque(3x)*
                        is_term_resized          resizeterm(3x)*
                        is_wintouched            curs_touch(3x)
                        isendwin                 curs_initscr(3x)
                        key_defined              key_defined(3x)*
                        key_name                 curs_util(3x)
                        keybound                 keybound(3x)*
                        keyname                  curs_util(3x)
                        keyok                    keyok(3x)*
                        keypad                   curs_inopts(3x)
                        killchar                 curs_termattrs(3x)
                        killwchar                curs_termattrs(3x)
                        leaveok                  curs_outopts(3x)

                        longname                 curs_termattrs(3x)
                        mcprint                  curs_print(3x)*
                        meta                     curs_inopts(3x)
                        mouse_trafo              curs_mouse(3x)*
                        mouseinterval            curs_mouse(3x)*
                        mousemask                curs_mouse(3x)*
                        move                     curs_move(3x)
                        mvadd_wch                curs_add_wch(3x)
                        mvadd_wchnstr            curs_add_wchstr(3x)
                        mvadd_wchstr             curs_add_wchstr(3x)
                        mvaddch                  curs_addch(3x)
                        mvaddchnstr              curs_addchstr(3x)
                        mvaddchstr               curs_addchstr(3x)
                        mvaddnstr                curs_addstr(3x)
                        mvaddnwstr               curs_addwstr(3x)
                        mvaddstr                 curs_addstr(3x)
                        mvaddwstr                curs_addwstr(3x)
                        mvchgat                  curs_attr(3x)
                        mvcur                    curs_terminfo(3x)
                        mvdelch                  curs_delch(3x)
                        mvderwin                 curs_window(3x)
                        mvget_wch                curs_get_wch(3x)
                        mvget_wstr               curs_get_wstr(3x)
                        mvgetch                  curs_getch(3x)
                        mvgetn_wstr              curs_get_wstr(3x)
                        mvgetnstr                curs_getstr(3x)
                        mvgetstr                 curs_getstr(3x)
                        mvhline                  curs_border(3x)
                        mvhline_set              curs_border_set(3x)
                        mvin_wch                 curs_in_wch(3x)
                        mvin_wchnstr             curs_in_wchstr(3x)
                        mvin_wchstr              curs_in_wchstr(3x)
                        mvinch                   curs_inch(3x)
                        mvinchnstr               curs_inchstr(3x)
                        mvinchstr                curs_inchstr(3x)
                        mvinnstr                 curs_instr(3x)
                        mvinnwstr                curs_inwstr(3x)
                        mvins_nwstr              curs_ins_wstr(3x)
                        mvins_wch                curs_ins_wch(3x)
                        mvins_wstr               curs_ins_wstr(3x)
                        mvinsch                  curs_insch(3x)
                        mvinsnstr                curs_insstr(3x)
                        mvinsstr                 curs_insstr(3x)
                        mvinstr                  curs_instr(3x)
                        mvinwstr                 curs_inwstr(3x)
                        mvprintw                 curs_printw(3x)
                        mvscanw                  curs_scanw(3x)
                        mvvline                  curs_border(3x)
                        mvvline_set              curs_border_set(3x)
                        mvwadd_wch               curs_add_wch(3x)
                        mvwadd_wchnstr           curs_add_wchstr(3x)
                        mvwadd_wchstr            curs_add_wchstr(3x)
                        mvwaddch                 curs_addch(3x)
                        mvwaddchnstr             curs_addchstr(3x)
                        mvwaddchstr              curs_addchstr(3x)
                        mvwaddnstr               curs_addstr(3x)
                        mvwaddnwstr              curs_addwstr(3x)
                        mvwaddstr                curs_addstr(3x)
                        mvwaddwstr               curs_addwstr(3x)
                        mvwchgat                 curs_attr(3x)
                        mvwdelch                 curs_delch(3x)
                        mvwget_wch               curs_get_wch(3x)
                        mvwget_wstr              curs_get_wstr(3x)
                        mvwgetch                 curs_getch(3x)
                        mvwgetn_wstr             curs_get_wstr(3x)

                        mvwgetnstr               curs_getstr(3x)
                        mvwgetstr                curs_getstr(3x)
                        mvwhline                 curs_border(3x)
                        mvwhline_set             curs_border_set(3x)
                        mvwin                    curs_window(3x)
                        mvwin_wch                curs_in_wch(3x)
                        mvwin_wchnstr            curs_in_wchstr(3x)
                        mvwin_wchstr             curs_in_wchstr(3x)
                        mvwinch                  curs_inch(3x)
                        mvwinchnstr              curs_inchstr(3x)
                        mvwinchstr               curs_inchstr(3x)
                        mvwinnstr                curs_instr(3x)
                        mvwinnwstr               curs_inwstr(3x)
                        mvwins_nwstr             curs_ins_wstr(3x)
                        mvwins_wch               curs_ins_wch(3x)
                        mvwins_wstr              curs_ins_wstr(3x)
                        mvwinsch                 curs_insch(3x)
                        mvwinsnstr               curs_insstr(3x)
                        mvwinsstr                curs_insstr(3x)
                        mvwinstr                 curs_instr(3x)
                        mvwinwstr                curs_inwstr(3x)
                        mvwprintw                curs_printw(3x)
                        mvwscanw                 curs_scanw(3x)
                        mvwvline                 curs_border(3x)
                        mvwvline_set             curs_border_set(3x)
                        napms                    curs_kernel(3x)
                        newpad                   curs_pad(3x)
                        newterm                  curs_initscr(3x)
                        newwin                   curs_window(3x)
                        nl                       curs_inopts(3x)
                        nocbreak                 curs_inopts(3x)
                        nodelay                  curs_inopts(3x)
                        noecho                   curs_inopts(3x)
                        nofilter                 curs_util(3x)*
                        nonl                     curs_inopts(3x)
                        noqiflush                curs_inopts(3x)
                        noraw                    curs_inopts(3x)
                        notimeout                curs_inopts(3x)
                        overlay                  curs_overlay(3x)
                        overwrite                curs_overlay(3x)
                        pair_content             curs_color(3x)
                        pecho_wchar              curs_pad(3x)*
                        pechochar                curs_pad(3x)
                        pnoutrefresh             curs_pad(3x)
                        prefresh                 curs_pad(3x)
                        printw                   curs_printw(3x)
                        putp                     curs_terminfo(3x)
                        putwin                   curs_util(3x)
                        qiflush                  curs_inopts(3x)
                        raw                      curs_inopts(3x)
                        redrawwin                curs_refresh(3x)
                        refresh                  curs_refresh(3x)
                        reset_color_pairs        curs_color(3x)*
                        reset_prog_mode          curs_kernel(3x)
                        reset_shell_mode         curs_kernel(3x)
                        resetty                  curs_kernel(3x)
                        resize_term              resizeterm(3x)*
                        resizeterm               resizeterm(3x)*
                        restartterm              curs_terminfo(3x)
                        ripoffline               curs_kernel(3x)
                        savetty                  curs_kernel(3x)
                        scanw                    curs_scanw(3x)
                        scr_dump                 curs_scr_dump(3x)
                        scr_init                 curs_scr_dump(3x)
                        scr_restore              curs_scr_dump(3x)

                        scr_set                  curs_scr_dump(3x)
                        scrl                     curs_scroll(3x)
                        scroll                   curs_scroll(3x)
                        scrollok                 curs_outopts(3x)
                        set_curterm              curs_terminfo(3x)
                        set_term                 curs_initscr(3x)
                        setcchar                 curs_getcchar(3x)
                        setscrreg                curs_outopts(3x)
                        setsyx                   curs_kernel(3x)
                        setupterm                curs_terminfo(3x)
                        slk_attr                 curs_slk(3x)*
                        slk_attr_off             curs_slk(3x)
                        slk_attr_on              curs_slk(3x)
                        slk_attr_set             curs_slk(3x)
                        slk_attroff              curs_slk(3x)
                        slk_attron               curs_slk(3x)
                        slk_attrset              curs_slk(3x)
                        slk_clear                curs_slk(3x)
                        slk_color                curs_slk(3x)
                        slk_init                 curs_slk(3x)
                        slk_label                curs_slk(3x)
                        slk_noutrefresh          curs_slk(3x)
                        slk_refresh              curs_slk(3x)
                        slk_restore              curs_slk(3x)
                        slk_set                  curs_slk(3x)
                        slk_touch                curs_slk(3x)
                        slk_wset                 curs_slk(3x)*
                        standend                 curs_attr(3x)
                        standout                 curs_attr(3x)
                        start_color              curs_color(3x)
                        subpad                   curs_pad(3x)
                        subwin                   curs_window(3x)
                        syncok                   curs_window(3x)
                        term_attrs               curs_termattrs(3x)
                        termattrs                curs_termattrs(3x)
                        termname                 curs_termattrs(3x)
                        tgetent                  curs_termcap(3x)
                        tgetflag                 curs_termcap(3x)
                        tgetnum                  curs_termcap(3x)
                        tgetstr                  curs_termcap(3x)
                        tgoto                    curs_termcap(3x)
                        tigetflag                curs_terminfo(3x)
                        tigetnum                 curs_terminfo(3x)
                        tigetstr                 curs_terminfo(3x)
                        timeout                  curs_inopts(3x)
                        tiparm                   curs_terminfo(3x)*
                        touchline                curs_touch(3x)
                        touchwin                 curs_touch(3x)
                        tparm                    curs_terminfo(3x)
                        tputs                    curs_termcap(3x)
                        tputs                    curs_terminfo(3x)
                        trace                    curs_trace(3x)*
                        typeahead                curs_inopts(3x)
                        unctrl                   curs_util(3x)
                        unget_wch                curs_get_wch(3x)
                        ungetch                  curs_getch(3x)
                        ungetmouse               curs_mouse(3x)*
                        untouchwin               curs_touch(3x)
                        use_default_colors       default_colors(3x)*
                        use_env                  curs_util(3x)
                        use_extended_names       curs_extend(3x)*
                        use_legacy_coding        legacy_coding(3x)*
                        use_tioctl               curs_util(3x)*
                        vid_attr                 curs_terminfo(3x)
                        vid_puts                 curs_terminfo(3x)

                        vidattr                  curs_terminfo(3x)
                        vidputs                  curs_terminfo(3x)
                        vline                    curs_border(3x)
                        vline_set                curs_border_set(3x)
                        vw_printw                curs_printw(3x)
                        vw_scanw                 curs_scanw(3x)
                        vwprintw                 curs_printw(3x)
                        vwscanw                  curs_scanw(3x)
                        wadd_wch                 curs_add_wch(3x)
                        wadd_wchnstr             curs_add_wchstr(3x)
                        wadd_wchstr              curs_add_wchstr(3x)
                        waddch                   curs_addch(3x)
                        waddchnstr               curs_addchstr(3x)
                        waddchstr                curs_addchstr(3x)
                        waddnstr                 curs_addstr(3x)
                        waddnwstr                curs_addwstr(3x)
                        waddstr                  curs_addstr(3x)
                        waddwstr                 curs_addwstr(3x)
                        wattr_get                curs_attr(3x)
                        wattr_off                curs_attr(3x)
                        wattr_on                 curs_attr(3x)
                        wattr_set                curs_attr(3x)
                        wattroff                 curs_attr(3x)
                        wattron                  curs_attr(3x)
                        wattrset                 curs_attr(3x)
                        wbkgd                    curs_bkgd(3x)
                        wbkgdset                 curs_bkgd(3x)
                        wbkgrnd                  curs_bkgrnd(3x)
                        wbkgrndset               curs_bkgrnd(3x)
                        wborder                  curs_border(3x)
                        wborder_set              curs_border_set(3x)
                        wchgat                   curs_attr(3x)
                        wclear                   curs_clear(3x)
                        wclrtobot                curs_clear(3x)
                        wclrtoeol                curs_clear(3x)
                        wcolor_set               curs_attr(3x)
                        wcursyncup               curs_window(3x)
                        wdelch                   curs_delch(3x)
                        wdeleteln                curs_deleteln(3x)
                        wecho_wchar              curs_add_wch(3x)
                        wechochar                curs_addch(3x)
                        wenclose                 curs_mouse(3x)*
                        werase                   curs_clear(3x)
                        wget_wch                 curs_get_wch(3x)
                        wget_wstr                curs_get_wstr(3x)
                        wgetbkgrnd               curs_bkgrnd(3x)
                        wgetch                   curs_getch(3x)
                        wgetdelay                curs_opaque(3x)*
                        wgetn_wstr               curs_get_wstr(3x)
                        wgetnstr                 curs_getstr(3x)
                        wgetparent               curs_opaque(3x)*
                        wgetscrreg               curs_opaque(3x)*
                        wgetstr                  curs_getstr(3x)
                        whline                   curs_border(3x)
                        whline_set               curs_border_set(3x)
                        win_wch                  curs_in_wch(3x)
                        win_wchnstr              curs_in_wchstr(3x)
                        win_wchstr               curs_in_wchstr(3x)
                        winch                    curs_inch(3x)
                        winchnstr                curs_inchstr(3x)
                        winchstr                 curs_inchstr(3x)
                        winnstr                  curs_instr(3x)
                        winnwstr                 curs_inwstr(3x)
                        wins_nwstr               curs_ins_wstr(3x)
                        wins_wch                 curs_ins_wch(3x)

                        wins_wstr                curs_ins_wstr(3x)
                        winsch                   curs_insch(3x)
                        winsdelln                curs_deleteln(3x)
                        winsertln                curs_deleteln(3x)
                        winsnstr                 curs_insstr(3x)
                        winsstr                  curs_insstr(3x)
                        winstr                   curs_instr(3x)
                        winwstr                  curs_inwstr(3x)
                        wmouse_trafo             curs_mouse(3x)*
                        wmove                    curs_move(3x)
                        wnoutrefresh             curs_refresh(3x)
                        wprintw                  curs_printw(3x)
                        wredrawln                curs_refresh(3x)
                        wrefresh                 curs_refresh(3x)
                        wresize                  wresize(3x)*
                        wscanw                   curs_scanw(3x)
                        wscrl                    curs_scroll(3x)
                        wsetscrreg               curs_outopts(3x)
                        wstandend                curs_attr(3x)
                        wstandout                curs_attr(3x)
                        wsyncdown                curs_window(3x)
                        wsyncup                  curs_window(3x)
                        wtimeout                 curs_inopts(3x)
                        wtouchln                 curs_touch(3x)
                        wunctrl                  curs_util(3x)
                        wvline                   curs_border(3x)
                        wvline_set               curs_border_set(3x)

           Depending on the configuration, additional sets  of  functions  may  be
           available:

              curs_memleaks(3x) - curses memory-leak checking

              curs_sp_funcs(3x) - curses screen-pointer extension

              curs_threads(3x) - curses thread support

              curs_trace(3x) - curses debugging routines

## RETURN VALUE

           Routines  that return an integer return ERR upon failure and an integer
           value other than ERR upon successful completion, unless otherwise noted
           in the routine descriptions.

           As  a  general  rule,  routines  check  for  null  pointers  passed  as
           parameters, and handle this as an error.

           All macros return  the  value  of  the  w  version,  except  setscrreg,
           wsetscrreg,  getyx,  getbegyx,  and  getmaxyx.   The  return  values of
           setscrreg, wsetscrreg, getyx,  getbegyx,  and  getmaxyx  are  undefined
           (i.e.,  these  should  not be used as the right-hand side of assignment
           statements).

           Functions with a "mv" prefix first  perform  a  cursor  movement  using
           wmove, and return an error if the position is outside the window, or if
           the window pointer  is  null.   Most  "mv"-prefixed  functions  (except
           variadic  functions  such  as mvprintw) are provided both as macros and
           functions.

           Routines that return pointers return NULL on error.

## ENVIRONMENT

           The following  environment  symbols  are  useful  for  customizing  the
           runtime  behavior of the ncurses library.  The most important ones have
           been already discussed in detail.

### CC command-character

           When set, change occurrences of the command_character (i.e., the  cmdch
           capability)  of  the  loaded  terminfo  entries  to  the  value of this
           variable.  Very few terminfo entries provide this feature.

           Because this name is also used in development environments to represent
           the C compiler's name, ncurses ignores it if it does not happen to be a
           single character.

### BAUDRATE

           The  debugging  library  checks  this  environment  variable  when  the
           application  has  redirected  output to a file.  The variable's numeric
           value is used for the baudrate.  If no value  is  found,  ncurses  uses
           9600.  This allows testers to construct repeatable test-cases that take
           into account costs that depend on baudrate.

### COLUMNS

           Specify the width of the screen in characters.  Applications running in
           a  windowing  environment  usually  are able to obtain the width of the
           window in which they are executing.  If neither the COLUMNS  value  nor
           the  terminal's  screen  size is available, ncurses uses the size which
           may be specified in the terminfo database (i.e., the cols capability).

           It is important that your  application  use  a  correct  size  for  the
           screen.   This  is  not always possible because your application may be
           running on a host which does not honor NAWS (Negotiations About  Window
           Size),  or  because  you  are  temporarily  running  as  another  user.
           However, setting COLUMNS and/or LINES overrides the  library's  use  of
           the screen size obtained from the operating system.

           Either  COLUMNS  or LINES symbols may be specified independently.  This
           is  mainly  useful  to  circumvent  legacy  misfeatures   of   terminal
           descriptions,  e.g.,  xterm  which commonly specifies a 65 line screen.
           For best results, lines and cols should not be specified in a  terminal
           description for terminals which are run as emulations.

           Use  the  use_env  function  to disable all use of external environment
           (but not including system calls) to determine the screen size.  Use the
           use_tioctl function to update COLUMNS or LINES to match the screen size
           obtained from system calls or the terminal database.

### ESCDELAY

           Specifies the total time, in milliseconds, for which ncurses will await
           a  character  sequence,  e.g., a function key.  The default value, 1000
           milliseconds, is enough for most uses.  However, it is made a  variable
           to accommodate unusual applications.

           The  most common instance where you may wish to change this value is to
           work with slow hosts, e.g., running on a network.  If the  host  cannot
           read  characters rapidly enough, it will have the same effect as if the
           terminal did not send characters  rapidly  enough.   The  library  will
           still see a timeout.

           Note  that  xterm  mouse  events  are built up from character sequences
           received from the xterm.   If  your  application  makes  heavy  use  of
           multiple-clicking,  you may wish to lengthen this default value because
           the timeout applies to the composed multi-click event as  well  as  the
           individual clicks.

           In addition to the environment variable, this implementation provides a
           global variable with the same name.  Portable applications  should  not
           rely  upon  the  presence  of  ESCDELAY in either form, but setting the
           environment variable rather than the global variable  does  not  create
           problems when compiling an application.

### HOME

           Tells  ncurses where your home directory is.  That is where it may read
           and write auxiliary terminal descriptions:

               $HOME/.termcap
               $HOME/.terminfo

### LINES

           Like COLUMNS, specify the height of  the  screen  in  characters.   See
           COLUMNS for a detailed description.

### MOUSE_BUTTONS_123

           This  applies  only  to  the  OS/2 EMX port.  It specifies the order of
           buttons on the mouse.  OS/2 numbers  a  3-button  mouse  inconsistently
           from other platforms:

               1 = left
               2 = right
               3 = middle.

           This variable lets you customize the mouse.  The variable must be three
           numeric digits 1-3 in any order, e.g.,  123  or  321.   If  it  is  not
           specified, ncurses uses 132.

### NCURSES_ASSUMED_COLORS

           Override  the compiled-in assumption that the terminal's default colors
           are  white-on-black  (see  default_colors(3x)).   You   may   set   the
           foreground  and  background color values with this environment variable
           by proving a 2-element list: foreground,background.   For  example,  to
           tell  ncurses  to  not  assume  anything  about the colors, set this to
           "-1,-1".  To make it green-on-black, set it  to  "2,0".   Any  positive
           value from zero to the terminfo max_colors value is allowed.

### NCURSES_CONSOLE2

           This applies only to the MinGW port of ncurses.

           The  Console2  program's  handling  of  the  Microsoft Console API call
           CreateConsoleScreenBuffer is defective.  Applications  which  use  this
           will hang.  However, it is possible to simulate the action of this call
           by mapping coordinates, explicitly saving and  restoring  the  original
           screen  contents.   Setting the environment variable NCGDB has the same
           effect.

### NCURSES_GPM_TERMS

           This applies only to ncurses configured to use the GPM interface.

           If present, the environment variable is a list of one or more  terminal
           names  against which the TERM environment variable is matched.  Setting
           it to an empty value disables the GPM  interface;  using  the  built-in
           support for xterm, etc.

           If the environment variable is absent, ncurses will attempt to open GPM
           if TERM contains "linux".

### NCURSES_NO_HARD_TABS

           Ncurses may use tabs as part of the cursor movement  optimization.   In
           some  cases,  your  terminal driver may not handle these properly.  Set
           this environment variable to disable the feature.  You can also  adjust
           your stty settings to avoid the problem.

### NCURSES_NO_MAGIC_COOKIE

           Some  terminals  use  a  magic-cookie  feature  which  requires special
           handling to  make  highlighting  and  other  video  attributes  display
           properly.   You  can  suppress  the  highlighting  entirely  for  these
           terminals by setting this environment variable.

### NCURSES_NO_PADDING

           Most of the terminal descriptions in the terminfo database are  written
           for  real  "hardware"  terminals.   Many  people use terminal emulators
           which run in a windowing environment and use curses-based applications.
           Terminal  emulators  can  duplicate  all  of the important aspects of a
           hardware terminal, but they do not  have  the  same  limitations.   The
           chief  limitation  of  a  hardware terminal from the standpoint of your
           application is the management of  dataflow,  i.e.,  timing.   Unless  a
           hardware  terminal  is  interfaced  into a terminal concentrator (which
           does flow control), it (or  your  application)  must  manage  dataflow,
           preventing  overruns.   The cheapest solution (no hardware cost) is for
           your program to do this by pausing after operations that  the  terminal
           does slowly, such as clearing the display.

           As  a  result,  many  terminal  descriptions (including the vt100) have
           delay times embedded.  You may wish to use these descriptions, but  not
           want to pay the performance penalty.

           Set  the  NCURSES_NO_PADDING  environment  variable  to disable all but
           mandatory padding.  Mandatory padding is used  as  a  part  of  special
           control sequences such as flash.

### NCURSES_NO_SETBUF

           This setting is obsolete.  Before changes

              o   started with 5.9 patch 20120825 and

              o   continued though 5.9 patch 20130126

           ncurses  enabled  buffered output during terminal initialization.  This
           was done (as in SVr4 curses)  for  performance  reasons.   For  testing
           purposes,  both  of  ncurses and certain applications, this feature was
           made optional.  Setting the NCURSES_NO_SETBUF variable disabled  output
           buffering,  leaving  the output in the original (usually line buffered)
           mode.

           In the current implementation, ncurses performs its own  buffering  and
           does  not require this workaround.  It does not modify the buffering of
           the standard output.

           The reason for the change was to make the behavior for  interrupts  and
           other   signals   more   robust.    One   drawback   is   that  certain
           nonconventional programs would mix ordinary stdio  calls  with  ncurses
           calls  and (usually) work.  This is no longer possible since ncurses is
           not using the buffered standard output but its own output (to the  same
           file  descriptor).  As a special case, the low-level calls such as putp
           still use the standard output.  But high-level curses calls do not.

### NCURSES_NO_UTF8_ACS

           During initialization, the ncurses library  checks  for  special  cases
           where VT100 line-drawing (and the corresponding alternate character set
           capabilities) described in  the  terminfo  are  known  to  be  missing.
           Specifically,  when  running  in  a  UTF-8  locale,  the  Linux console
           emulator and the GNU screen program ignore these.  Ncurses  checks  the
           TERM  environment  variable  for  these.   For other special cases, you
           should set this environment variable.  Doing this tells ncurses to  use
           Unicode values which correspond to the VT100 line-drawing glyphs.  That
           works for the special cases cited, and is likely to work  for  terminal
           emulators.

           When  setting  this  variable,  you  should  set it to a nonzero value.
           Setting it to zero (or to a nonnumber) disables the special  check  for
           "linux" and "screen".

           As  an  alternative  to the environment variable, ncurses checks for an
           extended terminfo capability U8.  This is a  numeric  capability  which
           can be compiled using tic -x.  For example

              # linux console, if patched to provide working
              # VT100 shift-in/shift-out, with corresponding font.
              linux-vt100|linux console with VT100 line-graphics,
                      U8#0, use=linux,

              # uxterm with vt100Graphics resource set to false
              xterm-utf8|xterm relying on UTF-8 line-graphics,
                      U8#1, use=xterm,

           The  name  "U8" is chosen to be two characters, to permit it to be used
           by applications that use ncurses' termcap interface.

### NCURSES_TRACE

           During  initialization,  the  ncurses  debugging  library  checks   the
           NCURSES_TRACE  environment  variable.   If  it is defined, to a numeric
           value, ncurses calls the  trace  function,  using  that  value  as  the
           argument.

           The  argument  values,  which  are defined in curses.h, provide several
           types  of  information.   When  running  with  traces   enabled,   your
           application will write the file trace to the current directory.

           See curs_trace(3x) for more information.

### TERM

           Denotes  your  terminal  type.   Each terminal type is distinct, though
           many are similar.

           TERM is commonly set by terminal emulators to help applications find  a
           workable   terminal  description.   Some  of  those  choose  a  popular
           approximation, e.g., "ansi", "vt100", "xterm" rather than an exact fit.
           Not  infrequently,  your  application  will  have  problems  with  that
           approach, e.g., incorrect function-key definitions.

           If you set TERM in your environment, it has no effect on the  operation
           of  the  terminal  emulator.  It only affects the way applications work
           within the terminal.  Likewise, as a general rule (xterm being  a  rare
           exception),  terminal  emulators  which  allow you to specify TERM as a
           parameter or configuration value do not change their behavior to  match
           that setting.

### TERMCAP

           If  the  ncurses  library  has  been  configured  with termcap support,
           ncurses will check for a terminal's description in termcap form  if  it
           is not available in the terminfo database.

           The TERMCAP environment variable contains either a terminal description
           (with newlines  stripped  out),  or  a  file  name  telling  where  the
           information denoted by the TERM environment variable exists.  In either
           case, setting it directs ncurses to ignore the  usual  place  for  this
           information, e.g., /etc/termcap.

### TERMINFO

           ncurses  can  be  configured  to read from multiple terminal databases.
           The TERMINFO variable overrides the location for the  default  terminal
           database.   Terminal  descriptions  (in  terminal format) are stored in
           terminal databases:

           o   Normally these are stored in a directory tree, using subdirectories
               named by the first letter of the terminal names therein.

               This is the scheme used in System V, which legacy Unix systems use,
               and the TERMINFO variable is used by curses applications  on  those
               systems to override the default location of the terminal database.

           o   If  ncurses  is  built  to use hashed databases, then each entry in
               this list may be the path of a hashed database file, e.g.,

                   /usr/share/terminfo.db

               rather than

                   /usr/share/terminfo/

               The hashed database uses less disk-space and  is  a  little  faster
               than  the  directory  tree.   However, some applications assume the
               existence of the directory tree, reading it  directly  rather  than
               using the terminfo library calls.

           o   If  ncurses  is  built  with  a  support  for reading termcap files
               directly, then an entry in this list may be the path of  a  termcap
               file.

           o   If the TERMINFO variable begins with "hex:" or "b64:", ncurses uses
               the remainder of that variable as a compiled terminal  description.
               You might produce the base64 format using infocmp(1m):

                   TERMINFO="$(infocmp -0 -Q2 -q)"
                   export TERMINFO

               The  compiled description is used if it corresponds to the terminal
               identified by the TERM variable.

           Setting TERMINFO is the simplest, but not the only way to set  location
           of  the  default  terminal  database.   The  complete  list of database
           locations in order follows:

              o   the last terminal database to which ncurses wrote,  if  any,  is
                  searched first

              o   the location specified by the TERMINFO environment variable

              o   $HOME/.terminfo

              o   locations listed in the TERMINFO_DIRS environment variable

              o   one  or  more  locations whose names are configured and compiled
                  into the ncurses library, i.e.,

                 o   no  default  value  (corresponding   to   the   TERMINFO_DIRS
                     variable)

                 o   /usr/share/terminfo (corresponding to the TERMINFO variable)

### TERMINFO_DIRS

           Specifies  a  list  of  locations  to search for terminal descriptions.
           Each location in the list is a terminal database as  described  in  the
           section  on  the  TERMINFO  variable.   The list is separated by colons
           (i.e., ":") on Unix, semicolons on OS/2 EMX.

           There is no corresponding feature  in  System  V  terminfo;  it  is  an
           extension developed for ncurses.

### TERMPATH

           If  TERMCAP  does not hold a file name then ncurses checks the TERMPATH
           environment variable.  This is a list of filenames separated by  spaces
           or colons (i.e., ":") on Unix, semicolons on OS/2 EMX.

           If  the  TERMPATH environment variable is not set, ncurses looks in the
           files

               /etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,

           in that order.

           The library may be configured to disregard the following variables when
           the  current  user  is the superuser (root), or if the application uses
           setuid or setgid permissions:

               $TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.

## ALTERNATE CONFIGURATIONS

           Several  different  configurations  are  possible,  depending  on   the
           configure  script  options used when building ncurses.  There are a few
           main options whose effects are visible to  the  applications  developer
           using ncurses:

           --disable-overwrite
                The standard include for ncurses is as noted in SYNOPSIS:

                    #include <curses.h>

                This  option  is  used to avoid filename conflicts when ncurses is
                not the main implementation of curses of the computer.  If ncurses
                is  installed  disabling  overwrite,  it  puts  its  headers  in a
                subdirectory, e.g.,

                    #include <ncurses/curses.h>

                It also omits a  symbolic  link  which  would  allow  you  to  use
                -lcurses to build executables.

           --enable-widec
                The   configure   script   renames   the   library   and  (if  the
                --disable-overwrite option is used) puts the  header  files  in  a
                different  subdirectory.   All  of  the  library  names have a "w"
                appended to them, i.e., instead of

                    -lncurses

                you link with

                    -lncursesw

                You must also enable the wide-character  features  in  the  header
                file  when  compiling  for  the  wide-character library to use the
                extended (wide-character) functions.   The  symbol  which  enables
                these features has changed since XSI Curses, Issue 4:

                o   Originally,  the  wide-character  feature  required the symbol
                    _XOPEN_SOURCE_EXTENDED  but  that  was  only  valid  for  XPG4
                    (1996).

                o   Later,  that was deemed conflicting with _XOPEN_SOURCE defined
                    to 500.

                o   As of mid-2018, none of the features  in  this  implementation
                    require  a  _XOPEN_SOURCE  feature greater than 600.  However,
                    X/Open Curses, Issue 7 (2009) recommends defining it to 700.

                o   Alternatively,  you  can  enable  the  feature   by   defining
                    NCURSES_WIDECHAR  with  the caveat that some other header file
                    than curses.h may require a specific value  for  _XOPEN_SOURCE
                    (or a system-specific symbol).

                The  curses.h  file  which  is  installed  for  the wide-character
                library is designed to be compatible  with  the  normal  library's
                header.   Only  the size of the WINDOW structure differs, and very
                few applications require more than a pointer to WINDOWs.

                If  the  headers  are  installed  allowing  overwrite,  the  wide-
                character  library's  headers  should  be installed last, to allow
                applications to be built using either library from the same set of
                headers.

           --with-pthread
                The  configure  script  renames  the  library.  All of the library
                names have a "t"  appended  to  them  (before  any  "w"  added  by
                --enable-widec).

                The global variables such as LINES are replaced by macros to allow
                read-only access.  At the same time, setter-functions are provided
                to  set  these  values.   Some applications (very few) may require
                changes to work with this convention.

           --with-shared

           --with-normal

           --with-debug

           --with-profile
                The shared and normal  (static)  library  names  differ  by  their
                suffixes,  e.g.,  libncurses.so  and  libncurses.a.  The debug and
                profiling libraries add a "_g"  and  a  "_p"  to  the  root  names
                respectively, e.g., libncurses_g.a and libncurses_p.a.

           --with-termlib
                Low-level  functions  which do not depend upon whether the library
                supports wide-characters, are provided in the tinfo library.

                By doing this, it is possible to share the tinfo  library  between
                wide/normal  configurations  as  well  as  reduce  the size of the
                library when only low-level functions are needed.

                Those functions are described in these pages:

                o   curs_extend(3x) - miscellaneous curses extensions

                o   curs_inopts(3x) - curses input options

                o   curs_kernel(3x) - low-level curses routines

                o   curs_termattrs(3x) - curses environment query routines

                o   curs_termcap(3x) - curses emulation of termcap

                o   curs_terminfo(3x) - curses interfaces to terminfo database

                o   curs_util(3x) - miscellaneous curses utility routines

           --with-trace
                The trace function normally resides in the debug library,  but  it
                is  sometimes  useful  to  configure  this  in the shared library.
                Configure scripts should check for the function's existence rather
                than assuming it is always in the debug library.

## FILES

           /usr/share/tabset
                directory   containing   initialization  files  for  the  terminal
                capability  database   /usr/share/terminfo   terminal   capability
                database

## SEE ALSO

           terminfo(5)  and  related  pages whose names begin "curs_" for detailed
           routine descriptions.
           curs_variables(3x)
           user_caps(5) for user-defined capabilities

## EXTENSIONS

           The ncurses library can be compiled with an option (-DUSE_GETCAP)  that
           falls  back  to  the  old-style /etc/termcap file if the terminal setup
           code cannot find a terminfo entry corresponding to TERM.  Use  of  this
           feature  is  not  recommended,  as  it  essentially  includes an entire
           termcap compiler in the ncurses startup code, at  significant  cost  in
           core and startup cycles.

           The  ncurses  library includes facilities for capturing mouse events on
           certain terminals (including xterm).   See  the  curs_mouse(3x)  manual
           page for details.

           The  ncurses  library  includes  facilities  for  responding  to window
           resizing  events,  e.g.,  when  running   in   an   xterm.    See   the
           resizeterm(3x)  and wresize(3x) manual pages for details.  In addition,
           the library may be configured with a SIGWINCH handler.

           The ncurses library extends the fixed set of function key  capabilities
           of  terminals by allowing the application designer to define additional
           key sequences at runtime.  See the define_key(3x) key_defined(3x),  and
           keyok(3x) manual pages for details.

           The  ncurses  library  can  exploit the capabilities of terminals which
           implement the ISO-6429 SGR 39 and  SGR  49  controls,  which  allow  an
           application  to  reset  the  terminal  to  its  original foreground and
           background colors.  From the users'  perspective,  the  application  is
           able  to  draw  colored  text  on  a  background  whose  color  is  set
           independently, providing better control over color contrasts.  See  the
           default_colors(3x) manual page for details.

           The  ncurses  library  includes  a  function  for directing application
           output  to  a  printer  attached  to  the  terminal  device.   See  the
           curs_print(3x) manual page for details.

## PORTABILITY

           The  ncurses  library  is intended to be BASE-level conformant with XSI
           Curses.   The  EXTENDED  XSI  Curses  functionality  (including   color
           support) is supported.

           A  small  number  of local differences (that is, individual differences
           between the XSI Curses and ncurses calls) are described in  PORTABILITY
           sections of the library man pages.

### Error checking

           In  many cases, X/Open Curses is vague about error conditions, omitting
           some of the SVr4 documentation.

           Unlike other  implementations,  this  one  checks  parameters  such  as
           pointers  to  WINDOW  structures to ensure they are not null.  The main
           reason for providing this  behavior  is  to  guard  against  programmer
           error.   The  standard interface does not provide a way for the library
           to tell an application which of several possible errors were  detected.
           Relying  on  this  (or  some other) extension will adversely affect the
           portability of curses applications.

### Extensions versus portability

           Most of the extensions provided by ncurses have not been  standardized.
           Some  have  been  incorporated  into  other  implementations,  such  as
           PDCurses or NetBSD curses.  Here are a few to consider:

           o   The routine has_key is not part of XPG4, nor is it present in SVr4.
               See the curs_getch(3x) manual page for details.

           o   The  routine  slk_attr  is  not  part of XPG4, nor is it present in
               SVr4.  See the curs_slk(3x) manual page for details.

           o   The routines getmouse, mousemask,  ungetmouse,  mouseinterval,  and
               wenclose  relating  to  mouse interfacing are not part of XPG4, nor
               are they present in SVr4.  See the curs_mouse(3x) manual  page  for
               details.

           o   The  routine  mcprint  was  not  present  in  any  previous  curses
               implementation.  See the curs_print(3x) manual page for details.

           o   The routine wresize is not part of XPG4, nor is it present in SVr4.
               See the wresize(3x) manual page for details.

           o   The   WINDOW  structure's  internal  details  can  be  hidden  from
               application programs.  See curs_opaque(3x) for  the  discussion  of
               is_scrollok, etc.

           o   This  implementation  can  be  configured  to  provide  rudimentary
               support for multi-threaded applications.  See curs_threads(3x)  for
               details.

           o   This  implementation  can  also  be  configured to provide a set of
               functions which improve the ability  to  manage  multiple  screens.
               See curs_sp_funcs(3x) for details.

### Padding differences

           In  historic  curses  versions, delays embedded in the capabilities cr,
           ind, cub1, ff and tab activated corresponding delay bits  in  the  UNIX
           tty driver.  In this implementation, all padding is done by sending NUL
           bytes.  This  method  is  slightly  more  expensive,  but  narrows  the
           interface  to the UNIX kernel significantly and increases the package's
           portability correspondingly.

### Header files

           The header file <curses.h>  automatically  includes  the  header  files
           <stdio.h> and <unctrl.h>.

           X/Open Curses has more to say, but does not finish the story:

               The  inclusion  of <curses.h> may make visible all symbols from the
               headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.

           Here is a more complete story:

           o   Starting  with  BSD  curses,  all  implementations  have   included
               <stdio.h>.

               BSD  curses  included  <curses.h>  and  <unctrl.h> from an internal
               header "curses.ext" ("ext" was a short name for externs).

               BSD curses used <stdio.h> internally (for printw  and  scanw),  but
               nothing in <curses.h> itself relied upon <stdio.h>.

           o   SVr2  curses  added newterm(3x), which relies upon <stdio.h>.  That
               is, the function prototype uses FILE.

               SVr4 curses added putwin and getwin, which also use <stdio.h>.

               X/Open Curses documents all three of these functions.

               SVr4 curses and X/Open Curses  do  not  require  the  developer  to
               include  <stdio.h>  before  including  <curses.h>.   Both  document
               curses showing <curses.h> as the only required header.

               As a result, standard <curses.h> will always include <stdio.h>.

           o   X/Open Curses  is  inconsistent  with  respect  to  SVr4  regarding
               <unctrl.h>.

               As   noted  in  curs_util(3x),  ncurses  includes  <unctrl.h>  from
               <curses.h> (like SVr4).

           o   X/Open's comments about <term.h> and <termios.h> may refer to HP-UX
               and AIX:

               HP-UX curses includes <term.h> from <curses.h> to declare setupterm
               in curses.h, but ncurses (and Solaris curses) do not.

               AIX curses includes <term.h> and <termios.h>.  Again, ncurses  (and
               Solaris curses) do not.

           o   X/Open  says  that <curses.h> may include <term.h>, but there is no
               requirement that it do that.

               Some  programs  use  functions  declared  in  both  <curses.h>  and
               <term.h>,  and  must include both headers in the same module.  Very
               old versions of AIX curses  required  including  <curses.h>  before
               including <term.h>.

               Because  ncurses  header files include the headers needed to define
               datatypes used in the headers, ncurses header files can be included
               in  any  order.  But for portability, you should include <curses.h>
               before <term.h>.

           o   X/Open Curses says "may make visible" because  including  a  header
               file does not necessarily make all symbols in it visible (there are
               ifdef's to consider).

               For instance, in ncurses <wchar.h> may be included  if  the  proper
               symbol  is defined, and if ncurses is configured for wide-character
               support.  If the header  is  included,  its  symbols  may  be  made
               visible.   That depends on the value used for _XOPEN_SOURCE feature
               test macro.

           o   X/Open Curses documents one required header,  in  a  special  case:
               <stdarg.h>   before  <curses.h>  to  prototype  the  vw_printw  and
               vw_scanw functions (as  well  as  the  obsolete  the  vwprintw  and
               vwscanw functions).  Each of those uses a va_list parameter.

               The  two  obsolete  functions  were  introduced in SVr3.  The other
               functions were introduced  in  X/Open  Curses.   In  between,  SVr4
               curses  provided  for  the  possibility  that  an application might
               include either <varargs.h> or <stdarg.h>.  Initially, that was done
               by  using  void*  for the va_list parameter.  Later, a special type
               (defined in <stdio.h>) was introduced, to allow for compiler  type-
               checking.  That special type is always available, because <stdio.h>
               is always included by <curses.h>.

               None of the X/Open Curses implementations require an application to
               include  <stdarg.h>  before  <curses.h>  because  they  either have
               allowed for a special type, or (like  ncurses)  include  <stdarg.h>
               directly to provide a portable interface.

## NOTES

           If  standard  output from a ncurses program is re-directed to something
           which is not a tty, screen updates will be directed to standard  error.
           This was an undocumented feature of AT&T System V Release 3 curses.

## AUTHORS

           Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey.  Based on pcurses
           by Pavel Curtis.

                                                                       ncurses(3x)