CRT screen handling and optimization package 

Curses Function


#include <curses.h>


The curses 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.

The ncurses routines emulate the curses library of System V Release 4 UNIX, and the XPG4 curses standard (XSI curses) but the ncurses library is freely redistributable in source form. Differences from the SVr4 curses are summarized under the EXTENSIONS section below and described in detail in the EXTENSIONS and BUGS sections of individual man pages.

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.

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

To initialize the routines, the routine initscr() or newterm() must be called before any of the other routines that deal with windows and screens are used. The routine endwin() must be called before exiting. To get character-at-a-time input without echoing (most interactive, screen oriented programs want this), the following sequence should be used:

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

Most programs would additionally use the sequence:

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

Before a curses program is run, the tab stops of the terminal should be set and its initialization strings, if defined, must be output. This can be done by executing the

tput init

command after the shell environment variable TERM has been exported. tset is usually responsible for doing this. [See terminfo for further details.]

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

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

Windows are referred to by variables declared as WINDOW *. These data structures are manipulated with routines described here and elsewhere in the ncurses manual pages. Among which 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() 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() for more information.

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

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

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


(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


and if that fails, it then checks


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

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

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

Routine and Argument Names

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

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

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

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

Option setting routines require a Boolean flag bf with the value TRUE or FALSE; bf is always of type bool. The variables ch and attrs below are always of type chtype. The types WINDOW, SCREEN, bool, and chtype are defined in <curses.h>. The type TERMINAL is defined in <term.h>. All other arguments are integers.

Routine Name Index

The following table lists each curses routine and the name of the manual 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
       addch                  curs_addch()
       addchnstr              curs_addchstr()
       addchstr               curs_addchstr()
       addnstr                curs_addstr()
       addstr                 curs_addstr()
       attroff                curs_attr()
       attron                 curs_attr()
       attrset                curs_attr()
       baudrate               curs_termattrs()
       beep                   curs_beep()
       bkgd                   curs_bkgd()
       bkgdset                curs_bkgd()
       border                 curs_border()
       box                    curs_border()
       can_change_color       curs_color()
       cbreak                 curs_inopts()
       clear                  curs_clear()
       clearok                curs_outopts()
       clrtobot               curs_clear()
       clrtoeol               curs_clear()
       color_content          curs_color()
       copywin                curs_overlay()
       curs_set               curs_kernel()
       def_prog_mode          curs_kernel()
       def_shell_mode         curs_kernel()
       del_curterm            curs_terminfo()
       delay_output           curs_util()
       delch                  curs_delch()
       deleteln               curs_deleteln()
       delscreen              curs_initscr()
       delwin                 curs_window()
       derwin                 curs_window()
       doupdate               curs_refresh()
       dupwin                 curs_window()
       echo                   curs_inopts()
       echochar               curs_addch()
       endwin                 curs_initscr()
       erase                  curs_clear()
       erasechar              curs_termattrs()
       filter                 curs_util()
       flash                  curs_beep()
       flushinp               curs_util()
       getbegyx               curs_getyx()
       getch                  curs_getch()
       getmaxyx               curs_getyx()
       getmouse               curs_mouse()*
       getparyx               curs_getyx()
       getstr                 curs_getstr()
       getsyx                 curs_kernel()
       getwin                 curs_util()
       getyx                  curs_getyx()
       halfdelay              curs_inopts()
       has_colors             curs_color()
       has_ic                 curs_termattrs()
       has_il                 curs_termattrs()
       has_key                curs_getch()*
       hline                  curs_border()
       idcok                  curs_outopts()
       idlok                  curs_outopts()
       immedok                curs_outopts()
       inch                   curs_inch()
       inchnstr               curs_inchstr()
       inchstr                curs_inchstr()
       init_color             curs_color()
       init_pair              curs_color()
       initscr                curs_initscr()
       innstr                 curs_instr()
       insch                  curs_insch()
       insdelln               curs_deleteln()
       insertln               curs_deleteln()
       insnstr                curs_insstr()
       insstr                 curs_insstr()
       instr                  curs_instr()
       intrflush              curs_inopts()
       is_linetouched         curs_touch()
       is_wintouched          curs_touch()
       isendwin               curs_initscr()
       keyname                curs_util()
       keypad                 curs_inopts()
       killchar               curs_termattrs()
       leaveok                curs_outopts()
       longname               curs_termattrs()
       mcprint                curs_print()*
       meta                   curs_inopts()
       mouseinterval          curs_mouse()*
       mousemask              curs_mouse()*
       move                   curs_move()
       mvaddch                curs_addch()
       mvaddchnstr            curs_addchstr()
       mvaddchstr             curs_addchstr()
       mvaddnstr              curs_addstr()
       mvaddstr               curs_addstr()
       mvcur                  curs_terminfo()
       mvdelch                curs_delch()
       mvderwin               curs_window()
       mvgetch                curs_getch()
       mvgetstr               curs_getstr()
       mvinch                 curs_inch()
       mvinchnstr             curs_inchstr()
       mvinchstr              curs_inchstr()
       mvinnstr               curs_instr()
       mvinsch                curs_insch()
       mvinsnstr              curs_insstr()
       mvinsstr               curs_insstr()
       mvinstr                curs_instr()
       mvprintw               curs_printw()
       mvscanw                curs_scanw()
       mvwaddch               curs_addch()
       mvwaddchnstr           curs_addchstr()
       mvwaddchstr            curs_addchstr()
       mvwaddnstr             curs_addstr()
       mvwaddstr              curs_addstr()
       mvwdelch               curs_delch()
       mvwgetch               curs_getch()
       mvwgetstr              curs_getstr()
       mvwin                  curs_window()
       mvwinch                curs_inch()
       mvwinchnstr            curs_inchstr()
       mvwinchstr             curs_inchstr()
       mvwinnstr              curs_instr()
       mvwinsch               curs_insch()
       mvwinsnstr             curs_insstr()
       mvwinsstr              curs_insstr()
       mvwinstr               curs_instr()
       mvwprintw              curs_printw()
       mvwscanw               curs_scanw()
       napms                  curs_kernel()
       newpad                 curs_pad()
       newterm                curs_initscr()
       newwin                 curs_window()
       nl                     curs_outopts()
       nocbreak               curs_inopts()
       nodelay                curs_inopts()
       noecho                 curs_inopts()
       nonl                   curs_outopts()
       noqiflush              curs_inopts()
       noraw                  curs_inopts()
       notimeout              curs_inopts()
       overlay                curs_overlay()
       overwrite              curs_overlay()
       pair_content           curs_color()
       pechochar              curs_pad()
       pnoutrefresh           curs_pad()
       prefresh               curs_pad()
       printw                 curs_printw()
       putp                   curs_terminfo()
       putwin                 curs_util()
       qiflush                curs_inopts()
       raw                    curs_inopts()
       redrawwin              curs_refresh()
       refresh                curs_refresh()
       reset_prog_mode        curs_kernel()
       reset_shell_mode       curs_kernel()
       resetty                curs_kernel()
       resizeterm             resizeterm()*
       restartterm            curs_terminfo()
       ripoffline             curs_kernel()
       savetty                curs_kernel()
       scanw                  curs_scanw()
       scr_dump               curs_scr_dump()
       scr_init               curs_scr_dump()
       scr_restore            curs_scr_dump()
       scr_set                curs_scr_dump()
       scrl                   curs_scroll()
       scroll                 curs_scroll()
       scrollok               curs_outopts()
       set_curterm            curs_terminfo()
       set_term               curs_initscr()
       setscrreg              curs_outopts()
       setsyx                 curs_kernel()
       setterm                curs_terminfo()
       setupterm              curs_terminfo()
       slk_attr               curs_slk()*
       slk_attroff            curs_slk()
       slk_attron             curs_slk()
       slk_attrset            curs_slk()
       slk_clear              curs_slk()
       slk_init               curs_slk()
       slk_label              curs_slk()
       slk_noutrefresh        curs_slk()
       slk_refresh            curs_slk()
       slk_restore            curs_slk()
       slk_set                curs_slk()
       slk_touch              curs_slk()
       standend               curs_attr()
       standout               curs_attr()
       start_color            curs_color()
       subpad                 curs_pad()
       subwin                 curs_window()
       syncok                 curs_window()
       termattrs              curs_termattrs()
       termname               curs_termattrs()
       tgetent                curs_termcap()
       tgetflag               curs_termcap()
       tgetnum                curs_termcap()
       tgetstr                curs_termcap()
       tgoto                  curs_termcap()
       tigetflag              curs_terminfo()
       tigetnum               curs_terminfo()
       tigetstr               curs_terminfo()
       timeout                curs_inopts()
       touchline              curs_touch()
       touchwin               curs_touch()
       tparm                  curs_terminfo()
       tputs                  curs_termcap()
       tputs                  curs_terminfo()
       typeahead              curs_inopts()
       unctrl                 curs_util()
       ungetch                curs_getch()
       ungetmouse             curs_mouse()*
       untouchwin             curs_touch()
       use_env                curs_util()
       vidattr                curs_terminfo()
       vidputs                curs_terminfo()
       vline                  curs_border()
       vwprintw               curs_printw()
       vwscanw                curs_scanw()
       waddch                 curs_addch()
       waddchnstr             curs_addchstr()
       waddchstr              curs_addchstr()
       waddnstr               curs_addstr()
       waddstr                curs_addstr()
       wattroff               curs_attr()
       wattron                curs_attr()
       wattrset               curs_attr()
       wbkgd                  curs_bkgd()
       wbkgdset               curs_clear()
       wclrtobot              curs_clear()
       wclrtoeol              curs_deleteln()
       wechochar              curs_addch()
       wenclose               curs_mouse()*
       werase                 curs_clear()
       wgetch                 curs_getch()
       wgetnstr               curs_getstr()
       wgetstr                curs_getstr()
       whline                 curs_border()
       winch                  curs_inch()
       winchnstr              curs_inchstr()
       winchstr               curs_inchstr()
       winnstr                curs_instr()
       winsch                 curs_insch()
       winsdelln              curs_deleteln()
       winsertln              curs_deleteln()
       winsnstr               curs_insstr()
       winsstr                curs_insstr()
       winstr                 curs_instr()
       wmove                  curs_move()
       wnoutrefresh           curs_refresh()
       wprintw                curs_printw()
       wredrawln              curs_refresh()
       wrefresh               curs_refresh()
       wresize                wresize()*
       wscanw                 curs_scanw()
       wscrl                  curs_scroll()
       wsetscrreg             curs_outopts()
       wstandend              curs_attr()
       wstandout              curs_attr()
       wsyncdown              curs_window()
       wsyncup                curs_window()
       wtimeout               curs_inopts()
       wtouchln               curs_touch()
       wvline                 curs_border()


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.

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

Routines that return pointers return NULL on error.


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

Compiling with -DTERMCAP_FILE changes the library's initialization sequence in a way intended to mimic the behavior of 4.4BSD curses. If there is no local or system terminfo entry matching TERM, then the library looks for termcap entries in the following places: (1) if TERMINFO is undefined, in the file named by TERMCAP_FILE; (2) if TERMINFO is defined and begins with a slash, it is interpreted as the name of a termcap file to search for TERM; (3) otherwise, if TERMINFO has a leading string that looks like a terminal entry name list, and it matches TERM, the contents of TERMINFO is interpreted as a termcap; (4) if TERMINFO looks like a termcap but doesn't match TERM, the termcap file is searched for among the colon-separated paths in the environment variable TERMPATHS if that is defined, and in ~/.termcap and the file value of TERMCAP_FILE() otherwise.

Versions of curses compiled on PC clones support display of the PC ROM characters (including ROM characters 0-31, which stock SVr4 curses cannot display). See the EXTENSIONS sections of curs_addch() and curs_attr().

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

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


The curses library is intended to be BASE-level conformant with the XSI Curses standard. Certain portions of the EXTENDED XSI Curses functionality (including color support) are supported. The following EXTENDED XSI Curses calls in support of wide (multibyte) characters are not yet implemented: addnwstr(), addwstr(), mvaddnwstr(), mvwaddnwstr(), mvaddwstr(), waddnwstr(), waddwstr(), add_wch(), wadd_wch(), mvadd_wch(), mvwadd_wch(), add_wchnstr(), add_wchstr(), wadd_wchnstr(), wadd_wchstr(), mvadd_wchnstr(), mvadd_wchstr(), mvwadd_wchnstr(), mvwadd_wchstr(), bkgrndset(), bkgrnd(), getbkgrnd(), wbkgrnd(), wbkgrndset(), wgetbkgrnd(), border_set(), wborder_set(), box_set(), hline_set(), mvhline_set(), mvvline_set(), mvwhline_set(), mvwvline_set(), whline_set(), vhline_set(), wvline_set(), echo_wchar(), wecho_wchar(), erasewchar(), killwchar(), get_wch(), mvget_wch(), mvwget_ch(), wget_wch(), getwchtype(), get_wstr(), getn_wstr(), wget_wstr(), wgetn_wstr(), mvget_wstr(), mvgetn_wstr(), mvwget_wstr(), mvwgetn_wstr(), innwstr(), inwstr(), winnwstr(), winwstr(), mvinnwstr(), mvinwstr(), mvwinnwstr(), mvwinwstr(), ins_nwstr(), ins_wstr(), mvins_nwstr(), mvins_wstr(), mvwins_nwstr(), mvwins_wstr(), wins_nwstr(), wins_wstr(), ins_wch(), wins_wch(), mvins_wch(), mvwins_wch(), in_wch(), win_wch(), mvin_wch(), mvwin_wch(), inwchstr(), inwchnstr(), winwchstr(), winwchnstr(), mvinwchstr(), mvinwchnstr(), mvinwchstr(), mvwinwchnstr.()

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

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

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

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() manual page for details.

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

The routine wresize() is not part of XPG4, nor is it present in SVr4. See the wresize() manual page 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 NUL sends. This method is slightly more expensive, but narrows the interface to the UNIX kernel significantly and increases the package's portability correspondingly.

In the XSI standard and SVr4 manual pages, many entry points have prototype arguments of the for char *const (or cchar_t *const, or wchar_t *const, or void *const). Depending on one's interpretation of the ANSI C standard (see section, these declarations are either (a) meaningless, or (b) meaningless and illegal. The declaration const char *x is a modifiable pointer to unmodifiable data, but char *const x' is an unmodifiable pointer to modifiable data. Given that C passes arguments by value, <type> *const as a formal type is at best dubious. Some compilers choke on the prototypes. Therefore, in this implementation, they have been changed to const <type> * globally.


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

If standard output from a curses 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.


Zeyd M. Ben-Halim, Eric S. Raymond. Descends from the original pcurses by Pavel Curtis.


PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition



PTC MKS Toolkit 10.4 Documentation Build 39.