# ncurses 3x 2025-04-05 ncurses 6.5 Library calls

    ncurses(3x)                      Library calls                     ncurses(3x)

## NAME

           ncurses - character-cell terminal interface with optimized output

## SYNOPSIS

           #include <curses.h>

## DESCRIPTION

           The  "new  curses" library offers the programmer a terminal-independent
           means of reading keyboard and mouse input and writing to character-cell
           displays  with  output  optimized  to minimize screen updates.  ncurses
           replaces the curses libraries from System V Release 4 Unix ("SVr4") and
           4.4BSD  Unix,  the  development  of  which  ceased  in the 1990s.  This
           document describes ncurses version 6.5 (patch 20250405).

           ncurses permits control of the terminal screen's contents;  abstraction
           and  subdivision thereof with windows and pads; acquisition of keyboard
           and mouse events; selection of color and rendering attributes (such  as
           bold  or  underline); the definition and use of soft label keys; access
           to the terminfo terminal capability database; a  termcap  compatibility
           interface;  and an abstraction of the system's API for manipulating the
           terminal (such as termios(3)).

           ncurses implements the interface described by  X/Open  Curses  Issue 7.
           In many behavioral details not standardized by X/Open, ncurses emulates
           the curses library of SVr4 and provides numerous useful extensions.

           ncurses man pages employ several sections to clarify matters  of  usage
           and interoperability with other curses implementations.

           o   "NOTES"  describes  issues  and  caveats  of  which any user of the
               ncurses API should be aware, such as limitations on the size of  an
               underlying  integral  type  or  the  availability of a preprocessor
               macro exclusive  of  a  function  definition  (which  prevents  its
               address   from   being   taken).    This   section  also  describes
               implementation details of significance to the programmer but  which
               are not standardized.

           o   "EXTENSIONS"  presents ncurses innovations beyond the X/Open Curses
               standard and/or the SVr4 curses implementation.   They  are  termed
               extensions  to  indicate  that they cannot be implemented solely by
               using the library API, but require access to the library's internal
               state.

           o   "PORTABILITY" discusses matters (beyond the exercise of extensions)
               that should be considered when writing to a curses standard, or for
               multiple implementations.

           o   "HISTORY"  examines  points  of  detail in ncurses and other curses
               implementations over the decades of their development, particularly
               where precedent or inertia have frustrated better design (and, in a
               few cases, where such inertia has been overcome).

           A curses application must be linked with the library; use the -lncurses
           option  to your compiler or linker.  A debugging version of the library
           may be available; if so, link with it using -lncurses_g.  (Your  system
           integrator may have installed these libraries such that you can use the
           options -lcurses and -lcurses_g, respectively.)  The ncurses_g  library
           logs  events  describing  ncurses actions to a file called trace in the
           current directory.  See section "ALTERNATE CONFIGURATIONS" below.

### Application Structure

           A  curses  application  uses  information  from  the   system   locale;
           setlocale(3) prepares it for curses library calls.

               setlocale(LC_ALL, "");

           If  the  locale  is  not  thus  initialized,  the  library assumes that
           characters are printable as in ISO 8859-1, to work with certain  legacy
           programs.   You  should initialize the locale; do not expect consistent
           behavior from the library when the locale has not been set up.

           initscr(3x) or newterm(3x) must be called to initialize  curses  before
           use of any functions that access or manipulate windows or screens.

           To  get  character-at-a-time input without echoing -- most interactive,
           screen-oriented programs want this -- use the following sequence.

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

           Most applications would perform further setup as follows.

               noqiflush();
               keypad(stdscr, TRUE);

           A curses program  then  often  enters  an  event-handling  loop.   Call
           endwin(3x) before exiting.

### Overview

           A  curses  library abstracts the terminal with a SCREEN data structure,
           and represents all or part  of  its  display  with  WINDOW  structures.
           Distinct  properties apply to each; for example, the line discipline of
           a typical Unix terminal driver is in one of three modes:  raw,  cbreak,
           or  canonical ("cooked").  In curses, the line discipline is a property
           of the screen, applying identically to all windows associated with it.

           A window is a rectangular grid of character cells,  addressed  by  line
           and column coordinates (y, x), with the upper left corner as (0, 0).  A
           window called stdscr, the same size as the terminal screen,  is  always
           available.  Create others with newwin(3x).

           A  curses  library does not manage overlapping windows (but see below).
           You can either use stdscr to manage one screen-filling window, or  tile
           the  screen  into  non-overlapping  windows  and not use stdscr at all.
           Mixing the two approaches will result in  unpredictable  and  undesired
           effects.

           Functions  permit  manipulation  of a window and the cursor identifying
           the cell within it at which  the  next  operation  will  occur.   Among
           those,  the  most  basic  are  move(3x)  and addch(3x): these place the
           cursor within and write a character to stdscr, respectively.

           Frequent changes to the terminal screen can cause unpleasant flicker or
           inefficient  use  of  the  communication channel to the device, so as a
           rule the library does not update it  automatically.   Therefore,  after
           using curses functions to accumulate a set of desired updates that make
           sense to present together, call refresh(3x) to tell the library to make
           the  user's  screen look like stdscr.  The library optimizes its output
           by computing a minimal volume of operations to mutate the  screen  from
           its   state  at  the  previous  refresh  to  the  new  one.   Effective
           optimization demands accurate information about  the  terminal  device:
           the  management of such information is the province of the terminfo(3x)
           API, a feature of every standard curses implementation.

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

           Many terminals support configuration of character cell  foreground  and
           background  colors  as  well  as  attributes, which cause characters to
           render in such modes as boldfaced, underlined,  or  in  reverse  video.
           See curs_color(3x) and curs_attr(3x).

           curses  predefines  constants for a small set of forms-drawing graphics
           corresponding to the DEC Alternate Character Set (ACS),  a  feature  of
           VT100 and other terminals.  See addch(3x).

           curses is implemented using the operating system's terminal driver; key
           events are received not as scan  codes  but  as  byte  sequences.   The
           driver  reports  graphical  keycaps (alphanumeric and punctuation keys,
           and  the  space)  as-is.    Everything   else,   including   the   tab,
           enter/return,  keypad, arrow, and function keys, appears to curses as a
           control character or a multibyte escape sequence.  curses can translate
           the latter into unique key codes.  See keypad(3x) and getch(3x).

           ncurses provides reimplementations of the SVr4 panel(3x), form(3x), and
           menu(3x)  libraries;  they  permit   overlapping   windows   and   ease
           construction of user interfaces with curses.

### Initialization

           The   selection  of  an  appropriate  value  of  TERM  in  the  process
           environment  is  essential  to  correct  curses  and  terminfo  library
           operation.   A  well-configured  system  selects  a  correct TERM value
           automatically;  tset(1)  may   assist   with   troubleshooting   exotic
           situations.

           If you change the terminal type, export the shell's TERM variable, then
           run tset(1) or the "tput  init"  command.   See  subsection  "Tabs  and
           Initialization" of terminfo(5).

           If  the  environment  variables  LINES  and  COLUMNS are set, or if the
           curses program is executing in a graphical windowing  environment,  the
           information  obtained  thence  overrides that obtained by terminfo.  An
           ncurses   extension   supports   resizable   terminal   displays;   see
           wresize(3x).

           If  the  environment  variable  TERMINFO  is  defined, a curses program
           checks first for  a  terminal  type  description  in  the  location  it
           identifies.   TERMINFO  is  useful  for developing type descriptions or
           when write permission to /usr/share/terminfo is not available.

           See section "ENVIRONMENT" below.

### Naming Conventions

           curses offers many functions in variant forms using a  regular  set  of
           alternatives  to the name of an elemental one.  Those prefixed with "w"
           require a WINDOW pointer argument;  those  with  a  "mv"  prefix  first
           perform cursor movement using wmove(3x); a "mvw" prefix indicates both.
           The "w" function is typically the elemental one; the  removal  of  this
           prefix usually indicates operation on stdscr.

           Four functions prefixed with "p" require a pad argument; see below.

           In  function  synopses,  ncurses man pages apply the following names to
           parameters.  We introduce the character types in the next subsection.

                    bf     a bool (TRUE or FALSE)
                    c      a char or int
                    ch     a chtype
                    wc     a wchar_t or wint_t
                    wch    a cchar_t
                    win    pointer to a WINDOW
                    pad    pointer to a WINDOW that is a pad
                    pair   a foreground/background color pair identifier

### Wide and Non-wide Character Configurations

           This  man  page  primarily  surveys  functions  that  appear   in   any
           configuration of the library.  There are two common configurations; see
           section "ALTERNATE CONFIGURATIONS" below.

           ncurses   is the library in its "non-wide" configuration, handling only
                     eight-bit  characters.   It  stores a character combined with
                     attributes and a color pair identifier  in  a  chtype  datum,
                     which  is  often  an  alias  of  int.   A  string  of  curses
                     characters is similar to a C char  string;  a  chtype  string
                     ends with an integral 0, the null curses character.

                     Attributes and a color pair identifier (with no corresponding
                     character) can be stored in variables  of  chtype  or  attr_t
                     type.   In either case, they are accessed via an integral bit
                     mask.

                     ncurses stores each cell of a WINDOW  as  a  chtype.   X/Open
                     Curses  does  not  specify the sizes of the character code or
                     color pair identifier, nor the quantity of attribute bits, in
                     chtype;  these  are  implementation-dependent.   ncurses uses
                     eight bits for the character code.  An application  requiring
                     a  wider  character  type, for instance to represent Unicode,
                     should use the wide-character API.

           ncursesw  is the library in its  "wide"  configuration,  which  handles
                     character encodings requiring a larger data type than char (a
                     byte-sized  type)  can  represent.   It  provides  additional
                     functions that complement those in the non-wide library where
                     the size of the underlying character type is significant.   A
                     somewhat  regular  naming convention relates many of the wide
                     variants to their non-wide  counterparts;  where  a  non-wide
                     function  name contains "ch" or "str", prefix it with "_w" to
                     obtain the wide counterpart.   For  example,  waddch  becomes
                     wadd_wch.   An  exception  is  ins_nwstr  (and its variants),
                     spelled thus instead of "insn_wstr".   (Exceptions  that  add
                     only "w" comprise addwstr, inwstr, and their variants.)

                     This  convention  is  inapplicable  to some non-wide function
                     names,  so  other  transformations  are  used  for  the  wide
                     configuration:  the  window  background  management  function
                     "bkgd"  becomes  "bkgrnd";  the  window  border-drawing   and
                     -clearing  functions  are suffixed with "_set"; and character
                     attribute  manipulation  functions   like   "attron"   become
                     "attr_on".

                     cchar_t  is a curses complex character and corresponds to the
                              non-wide configuration's chtype.  It is a  structure
                              type   because  it  requires  more  storage  than  a
                              standard scalar type offers.  A character  code  may
                              not  be  representable  as a char, and moreover more
                              than one character may occupy a cell (as with accent
                              marks  and  other diacritics).  Each character is of
                              type  wchar_t;  a  complex  character  contains  one
                              spacing  character  and  zero  or  more  non-spacing
                              characters  (see  below).   A  string   of   complex
                              characters  ends with a cchar_t whose wchar_t member
                              is the null wide character.  Attributes and a  color
                              pair identifier are stored in separate fields of the
                              structure,  not  combined  into  an  integer  as  in
                              chtype.

                     ncurses   stores   each  cell  of  a  WINDOW  as  a  cchar_t.
                     setcchar(3x) and  getcchar(3x)  store  and  retrieve  cchar_t
                     data.

                     The  wide  library  API  of ncurses depends on two data types
                     standardized by ISO C95.

                     wchar_t  stores a wide character.  Like chtype, it may be  an
                              alias  of int.  Depending on the character encoding,
                              a wide character may be  spacing,  meaning  that  it
                              occupies  a  character  cell by itself and typically
                              accompanies  cursor  advancement,  or   non-spacing,
                              meaning  that it occupies the same cell as a spacing
                              character, is often regarded as a "modifier" of  the
                              base  glyph  with  which  it combines, and typically
                              does not advance the cursor.

                     wint_t   can  store  a  wchar_t   or   the   constant   WEOF,
                              analogously  to the int-sized character manipulation
                              functions of ISO C and its constant EOF.

### Function Name Index

           The following table lists the curses functions provided in the non-wide
           and  wide  APIs  and  the  corresponding  man pages that describe them.
           Those flagged with  "*"  are  ncurses-specific,  neither  described  by
           X/Open Curses nor present in SVr4.

                        curses Function Name     Man Page
                        ---------------------------------------------
                        COLOR_PAIR               curs_color(3x)
                        PAIR_NUMBER              curs_color(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_escdelay             curs_threads(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_cbreak                curs_inopts(3x)*
                        is_cleared               curs_opaque(3x)*
                        is_echo                  curs_inopts(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_nl                    curs_inopts(3x)*
                        is_nodelay               curs_opaque(3x)*
                        is_notimeout             curs_opaque(3x)*
                        is_pad                   curs_opaque(3x)*
                        is_raw                   curs_inopts(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_kernel(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_escdelay             curs_threads(3x)*
                        set_tabsize              curs_threads(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)
                        tiparm_s                 curs_terminfo(3x)*
                        tiscan_s                 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_screen               curs_threads(3x)*
                        use_tioctl               curs_util(3x)*
                        use_window               curs_threads(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)

           ncurses's    screen-pointer   extension   adds   additional   functions
           corresponding to many of the above, each  with  an  "_sp"  suffix;  see
           curs_sp_funcs(3x).

           The  availability  of  some  extensions is configurable when ncurses is
           compiled; see  sections  "ALTERNATE  CONFIGURATIONS"  and  "EXTENSIONS"
           below.

## RETURN VALUE

           Unless  otherwise  noted,  functions  that  return  integers return the
           constants OK on success and ERR  on  failure;  see  curs_variables(3x).
           Functions  that  return  pointers  return  NULL on failure.  Typically,
           ncurses treats a null pointer passed  as  a  function  parameter  as  a
           failure.   Functions  prefixed  with "mv" first perform cursor movement
           and fail if the position (y, x) is outside the window boundaries.

## ENVIRONMENT

           The following  symbols  from  the  process  environment  customize  the
           runtime   behavior   of  ncurses  applications.   The  library  may  be
           configured  to  disregard  the   variables   TERMINFO,   TERMINFO_DIRS,
           TERMPATH,  and  HOME,  if  the  user  is  the  superuser (root), or the
           application uses setuid(2) or setgid(2).

### BAUDRATE

           The debugging library checks this variable  when  the  application  has
           redirected  output to a file.  ncurses interprets its integral value as
           the terminal's line speed in bits per second.  If that value is  absent
           or  invalid,  ncurses  uses  9600.   This  feature allows developers to
           construct repeatable test cases that  take  into  account  optimization
           decisions that depend on the terminal's line speed.

### CC (command character)

           When  set,  the  command_character  (cmdch)  capability value of loaded
           terminfo entries changes to the value of this variable.  Very few term-
           info entries provide this feature.

           Because this name is also used in development environments to store the
           C compiler's name, ncurses ignores its value if it is not one character
           in length.

### COLUMNS

           This  variable  specifies  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.  ncurses
           enforces an upper limit of 512 when reading the value.  If  COLUMNS  is
           not  defined  and  the terminal's screen size is not available from the
           terminal driver, ncurses uses the size specified by the columns  (cols)
           capability  of  the  terminal type's entry in the terminfo database, if
           any.

           It is important that your application  use  the  correct  screen  size.
           Automatic   detection   thereof  is  not  always  possible  because  an
           application may  be  running  on  a  host  that  does  not  honor  NAWS
           (Negotiations  About  Window  Size)  or as a different user ID than the
           owner of the  terminal  device  file.   Setting  COLUMNS  and/or  LINES
           overrides  the  library's  use  of  the  screen  size obtained from the
           operating system.

           The COLUMNS and LINES variables may be specified  independently.   This
           property  is  useful  to circumvent misfeatures of legacy terminal type
           descriptions; xterm(1)  descriptions  specifying  65  lines  were  once
           notorious.    For   best  results,  avoid  specifying  cols  and  lines
           capability codes in terminfo descriptions of terminal emulators.

           use_env(3x) can disable use of the process environment  in  determining
           the  screen size.  use_tioctl(3x) can update COLUMNS and LINES to match
           the screen size obtained from system calls or the terminal database.

### ESCDELAY

           For curses to distinguish the ESC character  resulting  from  a  user's
           press  of  the  "Escape"  key on the input device from one beginning an
           escape sequence (as commonly produced by function keys), it waits after
           receiving  the  escape  character  to  see  if  further  characters are
           available on the input  stream  within  a  short  interval.   A  global
           variable  ESCDELAY  stores  this interval in milliseconds.  The default
           value of 1000 (one second) is adequate for most uses.  This environment
           variable  overrides  it;  ncurses enforces an upper limit of 30,000 (30
           seconds) when reading the value.

           The most common instance where you may wish to change this value is  to
           work with a remote host over a slow communication channel.  If the host
           running a curses application does not  receive  the  characters  of  an
           escape  sequence  in a timely manner, the library can interpret them as
           multiple key stroke events.

           xterm(1) mouse events are a form of escape sequence; therefore, if your
           application  makes  heavy  use  of  multiple-clicking,  you may wish to
           lengthen the default value because the delay applies to  the  composite
           multi-click event as well as the individual clicks.

           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.

           If  keypad(3x)  is  disabled  for  the curses window receiving input, a
           program must disambiguate escape sequences itself.

### HOME

           ncurses may read and write auxiliary terminal descriptions in  .termcap
           and .terminfo files in the user's home directory.

### LINES

           This  counterpart  to  COLUMNS  specifies  the  height of the screen in
           characters.  The corresponding terminfo capability and code  is  lines.
           See the description of the COLUMNS variable above.

### MOUSE_BUTTONS_123

           (OS/2  EMX  port only) OS/2 numbers a three-button mouse inconsistently
           with other platforms, such that 1 is the left button, 2 the right,  and
           3  the  middle.   This  variable customizes the mouse button numbering.
           Its value must be three digits 1-3 in any order.  By  default,  ncurses
           assumes a numbering of "132".

### NCURSES_ASSUMED_COLORS

           If  set,  this  variable  overrides  the  ncurses library's compiled-in
           assumption that the terminal's default colors are white on  black;  see
           default_colors(3x).   Set  the  foreground  and background color values
           with this environment variable  by  assigning  it  two  integer  values
           separated  by  a  comma,  indicating  foregound  and  background  color
           numbers, respectively.

           For example, to tell ncurses not to assume anything about  the  colors,
           use  a  value  of  "-1,-1".   To make the default color scheme green on
           black, use "2,0".  ncurses accepts integral values from -1  up  to  the
           value of the terminfo max_colors (colors) capability.

### NCURSES_CONSOLE2

           (MinGW   port  only)  The  Console2  program  defectively  handles  the
           Microsoft Console  API  call  CreateConsoleScreenBuffer.   Applications
           that  use it 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

           (Linux only) When ncurses is configured to use the GPM interface,  this
           variable  may  list  one  or  more  terminal  type  names, delimited by
           vertical bars (|) or colons (:), against which the TERM  variable  (see
           below)  is  matched.   An empty value disables the GPM interface, using
           ncurses's built-in support for xterm(1) mouse  protocols  instead.   If
           the  variable  is absent, ncurses attempts to open GPM if TERM contains
           "linux".

### NCURSES_NO_HARD_TABS

           ncurses may use tab characters in  cursor  movement  optimization.   In
           some  cases,  your  terminal  driver may not handle them properly.  Set
           this environment variable to any value to disable the feature.  You can
           also adjust your stty(1) settings to avoid the problem.

### NCURSES_NO_MAGIC_COOKIE

           Many  terminals  store  video  attributes  as a property of a character
           cell, as curses does.  Historically, some  recorded  changes  in  video
           attributes  as  data  that  logically  occupies  character cells on the
           display, switching attributes on or off, similarly to tags in a  markup
           language;  these  are  termed "magic cookies", and must be subsequently
           overprinted.  If the terminfo entry for your  terminal  type  does  not
           adequately describe its handling of magic cookies, set this variable to
           any value to instruct ncurses to disable attributes entirely.

### NCURSES_NO_PADDING

           Most  terminal  type  descriptions  in  the  terminfo  database  detail
           hardware   devices.   Many  people  use  curses-based  applications  in
           terminal emulator programs that run in a windowing environment.   These
           programs  can  duplicate  all  of  the important features of a hardware
           terminal, but often lack their limitations.  Chief among  these  absent
           drawbacks is the problem of data flow management; that is, limiting the
           speed of communication to what the hardware  could  handle.   Unless  a
           hardware  terminal  is  interfaced  into a terminal concentrator (which
           does flow control), an application must manage flow itself  to  prevent
           overruns and data loss.

           A  solution  that  comes  at  no hardware cost is for an application to
           pause after directing a  terminal  to  execute  an  operation  that  it
           performs  slowly,  such  as  clearing  the display.  Many terminal type
           descriptions, including that for the VT100, embed delay  specifications
           in  capabilities.   You  may  wish  to  use these terminal descriptions
           without paying the performance penalty.  Set NCURSES_NO_PADDING to  any
           value  to disable all but mandatory padding.  Mandatory padding is used
           by such terminal capabilities as flash_screen (flash).

### NCURSES_NO_SETBUF

           (Obsolete) Prior to internal changes developed in ncurses 5.9  (patches
           20120825  through 20130126), the library used setbuf(3) to enable fully
           buffered output when initializing the terminal.  This was done,  as  in
           SVr4  curses,  to  increase performance.  For testing purposes, both of
           ncurses and of certain applications, this feature  was  made  optional.
           Setting  this  variable  disabled  output buffering, leaving the output
           stream in the original (usually line-buffered) mode.

           Nowadays, ncurses performs its own buffering and does not require  this
           workaround;  it  does  not  modify the buffering of the standard output
           stream.  This approach makes signal handling, as for  interrupts,  more
           robust.   A  drawback  is  that  certain  unconventional programs mixed
           stdio(3) calls with ncurses calls and (usually) got the  behavior  they
           expected.   This  is  no longer the case; ncurses does not write to the
           standard output file descriptor through a stdio-buffered stream.

           As a special case, low-level API calls such as putp(3x) still  use  the
           standard  output stream.  High-level curses calls such as printw(3x) do
           not.

### NCURSES_NO_UTF8_ACS

           At initialization, ncurses inspects the TERM environment  variable  for
           special   cases   where   VT100   forms-drawing   characters  (and  the
           corresponding alternate character set terminfo capabilities) are  known
           to  be  unsupported  by  terminal  types  that  otherwise  claim  VT100
           compatibility.  Specifically, when running in a UTF-8 locale, the Linux
           virtual  console device and the GNU screen(1) program ignore them.  Set
           this  variable  to  a  nonzero  value  to  instruct  ncurses  that  the
           terminal's ACS support is broken; the library then outputs Unicode code
           points that correspond to the forms-drawing characters.  Set it to zero
           (or a non-integer) to disable the special check for terminal type names
           matching "linux" or "screen", directing ncurses to assume that the  ACS
           feature works if the terminal type description advertises it.

           As  an  alternative  to  use  of  this  variable, ncurses checks for an
           extended terminfo numeric capability U8 that can be compiled using "tic
           -x".  Examples follow.

              # 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  two-character name "U8" was chosen to permit its use via ncurses's
           termcap interface.

### NCURSES_TRACE

           At initialization, ncurses (in its debugging configuration) checks  for
           this  variable's  presence.   If  defined  with  an integral value, the
           library calls curses_trace(3x) with that value as the argument.

### TERM

           The TERM variable denotes the terminal type.  Each is distinct,  though
           many  are  similar.   It  is commonly set by terminal emulators to help
           applications find a  workable  terminal  description.   Some  choose  a
           popular  approximation  such as "ansi", "vt100", or "xterm" rather than
           an exact fit to their capabilities.  Not infrequently,  an  application
           will  have  problems  with that approach; for example, a key stroke may
           not operate  correctly,  or  produce  no  effect  but  seeming  garbage
           characters on the screen.

           Setting  TERM  has  no effect on hardware operation; it affects the way
           applications communicate with the terminal.   Likewise,  as  a  general
           rule  (xterm(1)  being a rare exception), terminal emulators that allow
           you to specify TERM as a parameter or configuration value do not change
           their behavior to match that setting.

### TERMCAP

           If ncurses is configured with termcap support, it checks for a terminal
           type description in termcap format if one in  terminfo  format  is  not
           available.   Setting  this variable directs ncurses to ignore the usual
           termcap database location, /etc/termcap; see TERMPATH  below.   TERMCAP
           should  contain  either  a terminal description (with newlines stripped
           out), or a file name indicating where the information required  by  the
           TERM environment variable is stored.

### TERMINFO

           ncurses  can  be configured to read terminal type description databases
           in various locations using different formats.  This variable  overrides
           the default location.

           o   Descriptions  in terminfo format are normally stored in a directory
               tree using subdirectories named for the common first letters of the
               terminal types named therein.  System V used this scheme.

           o   If ncurses is configured to use hashed databases, then TERMINFO may
               name its location,  such  as  /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, and read it directly rather than using the terminfo
           API.

           o   If ncurses is configured with termcap support,  this  variable  may
               contain the location of a termcap file.

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

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

               ncurses uses the compiled description only if it corresponds to the
               terminal type identified by TERM.

           Setting TERMINFO is the simplest, but  not  the  only,  way  to  direct
           ncurses to a terminal database.  The search path is as follows.

           o   the last terminal database to which the running ncurses application
               wrote, if any

           o   the location specified by the TERMINFO environment variable

           o   $HOME/.terminfo

           o   locations listed in the TERMINFO_DIRS environment variable

           o   location(s) configured and compiled into ncurses

               o   /usr/share/terminfo

### TERMINFO_DIRS

           This variable specifies a list of locations, akin  to  PATH,  in  which
           ncurses  searches  for  the  terminal  type  descriptions  described by
           TERMINFO above.  The list items are separated by  colons  on  Unix  and
           semicolons  on  OS/2  EMX.   System V  terminfo  lacks  a corresponding
           feature; TERMINFO_DIRS is an ncurses extension.

### TERMPATH

           If TERMCAP does not hold a terminal type description or file name, then
           ncurses  checks  the contents of TERMPATH, a list of locations, akin to
           PATH, in which it searches for termcap terminal type descriptions.  The
           list items are separated by colons on Unix and semicolons on OS/2 EMX.

           If both TERMCAP and TERMPATH are unset or invalid, ncurses searches for
           the files /etc/termcap, /usr/share/misc/termcap, and $HOME/.termcap, in
           that order.

## ALTERNATE CONFIGURATIONS

           Many  different  ncurses configurations are possible, determined by the
           options given to the configure script when building the  library.   Run
           the  script  with  the  --help option to peruse them all.  A few are of
           particular significance to the application developer employing ncurses.

           --disable-overwrite
                The standard C preprocessor inclusion for the curses library is as
                follows.

                    #include <curses.h>

                This  option  is used to avoid file name conflicts between ncurses
                and an existing curses installation on the system.  If ncurses  is
                installed  disabling  overwrite,  it  puts  its  header files in a
                subdirectory.  Here is an example.

                    #include <ncurses/curses.h>

                Installation also omits a  symbolic  link  that  would  cause  the
                compiler's  -lcurses  option  to  link  object  files with ncurses
                instead of the system curses library.

                The directory used by this configuration of ncurses  is  shown  in
                section "SYNOPSIS" above.

           --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 X/Open 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 an _XOPEN_SOURCE value
                    of 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 header file other
                    than curses.h may require a specific value  for  _XOPEN_SOURCE
                    (or a system-specific symbol).

                The  curses.h header file installed for the wide-character library
                is designed to be compatible with the non-wide  library's  header.
                Only  the  size  of the WINDOW structure differs; few applications
                require more than pointers to WINDOW.

                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).

                ncursest and ncursestw replace global variables such as LINES with
                macros allowing read-only access.  At the same time, they  provide
                functions  to  set  these  values.   Very few applications 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  roots  of  these
                respective  names, forming libncurses_g.so and libncurses_p.a, for
                example.

           --with-termlib
                This option configures ncurses to provide low-level functions that
                do  not  depend  upon  wide-character  support  in a library names
                tinfo.

                This arrangement enables tinfo to be shared  between  ncurses  and
                ncursesw  libraries  as well as application linking and/or loading
                times when it requires only low-level functions.

                The following pages describe low-level curses functions.

                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 interface 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 expose it in the shared or static library.
                Configuration scripts should check for  the  function's  existence
                rather than assuming it is confined to the debug library.

## FILES

           /usr/share/tabset
                  tab stop initialization database

           /usr/share/terminfo
                  compiled terminal capability database

## NOTES

           X/Open  Curses permits most functions it specifies to be made available
           as macros as well.  ncurses does so

           o   for functions that return values via their parameters,

           o   to support obsolete features,

           o   to reuse functions (for example, those that move the cursor  before
               another operation), and

           o   in a few special cases.

           If  the  standard  output  file  descriptor  of  an  ncurses program is
           redirected to something that is not  a  terminal  device,  the  library
           writes  screen updates to the standard error file descriptor.  This was
           an undocumented feature of SVr3 curses.

           See subsection  "Header  Files"  below  regarding  symbols  exposed  by
           inclusion of curses.h.

## EXTENSIONS

           ncurses  enables  an  application  to  capture  mouse events on certain
           terminals, including xterm(1); see curs_mouse(3x).

           ncurses provides a means of responding to window  resizing  events,  as
           when  running in a GUI terminal emulator application such as xterm; see
           resizeterm(3x) and wresize(3x).

           ncurses allows an application to query the terminal for the presence of
           a wide variety of special keys; see has_key(3x).

           ncurses extends the fixed set of function key capabilities specified by
           X/Open  Curses  by  allowing  the  application  programmer  to   define
           additional  key events at runtime; see define_key(3x), key_defined(3x),
           keybound(3x), and keyok(3x).

           ncurses  can  exploit  the  capabilities  of   terminals   implementing
           ISO 6429/ECMA-48   SGR 39   and   SGR 49   sequences,  which  allow  an
           application to reset  the  terminal  to  its  original  foreground  and
           background  colors.  From a user's perspective, the application is able
           to draw colored text on a background whose color is set  independently,
           providing better control over color contrasts.  See default_colors(3x).

           An  ncurses  application  can  eschew  knowledge  of  SCREEN and WINDOW
           structure  internals,  instead  using  accessor   functions   such   as
           is_cbreak(3x) and is_scrollok(3x).

           ncurses  enables  an  application  to  direct  its  output to a printer
           attached to the terminal device; see curs_print(3x).

           ncurses offers slk_attr(3x) as a counterpart of attr_get(3x) for  soft-
           label  key lines, and extended_slk_color(3x) as a form of slk_color(3x)
           that can gather color  information  from  them  when  many  colors  are
           supported.

           ncurses    permits   modification   of   unctrl(3x)'s   behavior;   see
           use_legacy_coding(3x).

           Rudimentary support for multi-threaded applications may  be  available;
           see curs_threads(3x).

           Functions  that ease the management of multiple screens can be exposed;
           see curs_sp_funcs(3x).

           To aid applications to debug their  memory  usage,  ncurses  optionally
           offers  functions  to  more  aggressively  free  memory  it dynamically
           allocates itself; see curs_memleaks(3x).

           The library facilitates auditing and troubleshooting of  its  behavior;
           see curs_trace(3x).

           Compiling  ncurses  with the option -DUSE_GETCAP causes it to fall back
           to reading /etc/termcap if the terminal setup code cannot find a  term-
           info  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 a cost in memory usage and application
           launch latency.

           PDCurses  and  NetBSD  curses  incorporate  some  ncurses   extensions.
           Individual man pages indicate where this is the case.

## PORTABILITY

           X/Open Curses defines two levels of conformance, "base" and "enhanced".
           The latter includes several additional features, such as wide-character
           and  color support.  ncurses intends base-level conformance with X/Open
           Curses, and supports all features of  its  enhanced  level  except  the
           untic utility.

           Differences  between  X/Open  Curses  and ncurses are documented in the
           "PORTABILITY" sections of applicable man pages.

### Error Checking

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

           Unlike  other  implementations, ncurses checks pointer parameters, such
           as those to WINDOW structures, to ensure that they are not null.   This
           is  done  primarily  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 occurred.  An application that relies
           on ncurses to check its function parameters  for  validity  limits  its
           portability and robustness.

### Padding Differences

           In  historical  curses implementations, delays embedded in the terminfo
           capabilities carriage_return (cr),  scroll_forward  (ind),  cursor_left
           (cub1), form_feed (ff), and tab (ht) activated corresponding delay bits
           in the Unix terminal driver.  ncurses performs all padding  by  sending
           NUL  bytes  to the device.  This method is slightly more expensive, but
           narrows  the  interface  to   the   Unix   kernel   significantly   and
           correspondingly increases the package's portability.

### Header Files

           The  header  file curses.h itself includes the header files stdio.h and
           unctrl.h.

           X/Open Curses has more to say,

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

           but does not finish the story.  A more complete account follows.

           o   The first curses, in 4BSD, provided a curses.h file.

               BSD  curses  code  included  curses.h and unctrl.h from an internal
               header file curses.ext, where "ext" abbreviated "externs".

               The implementations of printw and scanw used undocumented  internal
               functions  of  the  standard I/O library (_doprnt and _doscan), but
               nothing in curses.h itself relied upon stdio.h.

           o   SVr2 curses added newterm, which relies upon  stdio.h  because  its
               function prototype employs the FILE type.

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

               X/Open Curses specifies all three of these functions.

               SVr4  curses  and  X/Open  Curses  do  not require the developer to
               include stdio.h before curses.h.  Both document use  of  curses  as
               requiring only curses.h.

               As a result, standard curses.h always includes stdio.h.

           o   X/Open  Curses  and  SVr4  curses  are inconsistent with respect to
               unctrl.h.

               As noted in curs_util(3x), ncurses includes unctrl.h from  curses.h
               (as SVr4 does).

           o   X/Open  Curses'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 Curses says that curses.h may include term.h, but  does  not
               require it to do so.

               Some  programs  use functions declared in both curses.h and term.h,
               and must include both header files in the same  module.   Very  old
               versions  of  AIX  curses  required  inclusion  of  curses.h before
               term.h.

               The header files supplied by ncurses include the  standard  library
               headers  required  for  its  declarations,  so ncurses's own header
               files can be included in any order.  For portability  even  to  old
               AIX systems, include curses.h before term.h.

           o   X/Open  Curses  says  "may make visible" because including a header
               file does not necessarily make visible all of  the  symbols  in  it
               (consider #ifdef and similar).

               For  instance, ncurses's curses.h may include wchar.h if the proper
               symbol is defined, and if ncurses is configured for  wide-character
               support.   If  wchar.h is included, its symbols may be made visible
               depending on the value of the _XOPEN_SOURCE feature test macro.

           o   X/Open Curses mandates an application's inclusion of one standard C
               library  header  in  a  special  case:  stdarg.h before curses.h to
               prototype the functions vw_printw and  vw_scanw  (as  well  as  the
               obsolete  vwprintw  and  vwscanw).   Each of these takes a variadic
               argument list, a va_list parameter, like that of printf(3).

               SVr3 curses introduced  the  two  obsolete  functions,  and  X/Open
               Curses  the  others.   In  between,  SVr4  curses  provided for the
               possibility that an application might include either  varargs.h  or
               stdarg.h.   These  represented  contrasting  approaches to handling
               variadic argument lists.  The older interface,  varargs.h,  used  a
               pointer  to char for variadic functions' va_list parameter.  Later,
               the list acquired its own standard data type, va_list,  defined  in
               stdarg.h,  empowering the compiler to check the types of a function
               call's actual parameters against the formal ones  declared  in  its
               prototype.

               No   conforming   implementations   of  X/Open  Curses  require  an
               application to include stdarg.h before curses.h because they either
               have  allowed  for  a  special type, or, like ncurses, they include
               stdarg.h themselves to provide a portable interface.

## AUTHORS

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

## SEE ALSO

           curs_variables(3x), terminfo(5), user_caps(5)

    ncurses 6.5                       2025-04-05                       ncurses(3x)