# 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 6.2 (patch 20200212).

           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 PORTABIL-
           ITY sections below and described in detail  in  the  respective  EXTEN-
           SIONS, PORTABILITY and BUGS sections of individual man pages.

           The  ncurses  library  also provides many useful extensions, i.e., fea-
           tures 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 manipula-
           tion; output to windows and pads; reading terminal input; control  over
           terminal  and  curses  input and output options; environment query rou-
           tines; color manipulation; use of soft label keys;  terminfo  capabili-
           ties; 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 exit-
           ing.

           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:

               nonl();
               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 environ-
           ment  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 charac-
           ters 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.  Mix-
           ing 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  informa-
           tion.

           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 val-
           ues.   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 pro-
           gram 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 com-
           piled 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 rou-
           tines.

### 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 coor-
           dinates.

           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 configura-
           tion of the library.   There  are  two  common  configurations  of  the
           library:

              ncurses
                   the "normal" library, which handles 8-bit characters.  The nor-
                   mal (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 charac-
                   ters (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 con-
                   vention 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 each curses routine and the name of the  man-
           ual  page  on  which  it  is  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)
                        _nc_free_and_exit        curs_memleaks(3x)*
                        _nc_freeall              curs_memleaks(3x)*
                        _nc_tracebits            curs_trace(3x)*
                        _traceattr               curs_trace(3x)*
                        _traceattr2              curs_trace(3x)*
                        _tracechar               curs_trace(3x)*
                        _tracechtype             curs_trace(3x)*
                        _tracechtype2            curs_trace(3x)*
                        _tracedump               curs_trace(3x)*
                        _tracef                  curs_trace(3x)*
                        _tracemouse              curs_trace(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_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)
                        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)*
                        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_outopts(3x)
                        nocbreak                 curs_inopts(3x)
                        nodelay                  curs_inopts(3x)
                        noecho                   curs_inopts(3x)
                        nofilter                 curs_util(3x)*
                        nonl                     curs_outopts(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)
                        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_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)
                        setterm                  curs_terminfo(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)
                        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)

## 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  parame-
           ters, 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).

           Routines that return pointers return NULL on error.

## ENVIRONMENT

           The  following  environment symbols are useful for customizing the run-
           time 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  vari-
           able.  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 appli-
           cation 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.   How-
           ever,  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 descrip-
           tions, e.g., xterm which commonly specifies a 65 line screen.  For best
           results,  lines and cols should not be specified in a terminal descrip-
           tion 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 multi-
           ple-clicking, you may wish to lengthen this default value  because  the
           timeout  applies to the composed multi-click event as well as the indi-
           vidual 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 COL-
           UMNS for a detailed description.

### MOUSE_BUTTONS_123

           This applies only to the OS/2 EMX port.  It specifies the order of but-
           tons  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 speci-
           fied, 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 fore-
           ground 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  Cre-
           ateConsoleScreenBuffer  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  han-
           dling to make highlighting and other video attributes display properly.
           You can suppress the highlighting entirely for these terminals by  set-
           ting 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, pre-
           venting 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 con-
           trol 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 pur-
           poses, 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  nonconven-
           tional  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  emula-
           tor  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 emula-
           tors.

           When setting this variable, you should set it to a nonzero value.  Set-
           ting  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 argu-
           ment.

           The argument values, which are defined  in  curses.h,  provide  several
           types  of information.  When running with traces enabled, your applica-
           tion 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 approxi-
           mation,  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 informa-
           tion denoted by the TERM environment variable exists.  In either  case,
           setting  it directs ncurses to ignore the usual place for this informa-
           tion, 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  loca-
           tions 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   /usr/local/ncurses/share/terminfo:/usr/share/terminfo (corre-
                     sponding 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 exten-
           sion 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 config-
           ure 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  subdi-
                rectory, 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  --dis-
                able-overwrite  option is used) puts the header files in a differ-
                ent 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-charac-
                ter library's headers should be installed last, to allow  applica-
                tions  to be built using either library from the same set of head-
                ers.

           --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 suf-
                fixes, e.g., libncurses.so and libncurses.a.  The debug  and  pro-
                filing  libraries  add a "_g" and a "_p" to the root names respec-
                tively, e.g., libncurses_g.a and libncurses_p.a.

           --with-trace
                The trace function normally resides in the debug library,  but  it
                is sometimes useful to configure this in the shared library.  Con-
                figure 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 capa-
                bility 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  term-
           cap  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 resiz-
           ing 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  back-
           ground 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_col-
           ors(3x) manual page for details.

           The ncurses library includes a function for directing application  out-
           put   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 sup-
           port) 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.

           Unlike other implementations, this one checks parameters such as point-
           ers  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.

           This implementation also contains several extensions:

           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 imple-
               mentation.  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 applica-
               tion programs.  See curs_opaque(3x) for the discussion of is_scrol-
               lok, etc.

           o   This  implementation  can be configured to provide rudimentary sup-
               port 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.

           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  inter-
           face  to  the  UNIX  kernel  significantly  and increases the package's
           portability correspondingly.

## NOTES

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

           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)