# curs_inopts 3x

    curs_inopts(3x)                                                curs_inopts(3x)

## NAME

           cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad, meta, nl,
           nonl, nodelay, notimeout, raw, noraw, qiflush, noqiflush, timeout,
           wtimeout, typeahead - curses input options

## SYNOPSIS

           #include <curses.h>

           int cbreak(void);
           int nocbreak(void);

           int echo(void);
           int noecho(void);

           int intrflush(WINDOW *win, bool bf);
           int keypad(WINDOW *win, bool bf);
           int meta(WINDOW *win, bool bf);
           int nodelay(WINDOW *win, bool bf);
           int notimeout(WINDOW *win, bool bf);

           int nl(void);
           int nonl(void);

           int raw(void);
           int noraw(void);

           void qiflush(void);
           void noqiflush(void);

           int halfdelay(int tenths);
           void timeout(int delay);
           void wtimeout(WINDOW *win, int delay);

           int typeahead(int fd);

## DESCRIPTION

           The ncurses library provides several functions which let an application
           change the way input from the terminal is handled.   Some  are  global,
           applying to all windows.  Others apply only to a specific window.  Win-
           dow-specific settings are not automatically applied to new  or  derived
           windows.   An  application must apply these to each window, if the same
           behavior is needed.

### cbreak/nocbreak

           Normally, the tty driver buffers typed characters until  a  newline  or
           carriage  return  is typed.  The cbreak routine disables line buffering
           and erase/kill character-processing (interrupt and flow control charac-
           ters  are  unaffected), making characters typed by the user immediately
           available to the program.  The nocbreak routine returns the terminal to
           normal (cooked) mode.

           Initially the terminal may or may not be in cbreak mode, as the mode is
           inherited; therefore, a program should call cbreak or nocbreak  explic-
           itly.   Most  interactive  programs  using  curses set the cbreak mode.
           Note that cbreak overrides raw.  [See curs_getch(3x) for  a  discussion
           of how these routines interact with echo and noecho.]

### echo/noecho

           The  echo  and  noecho routines control whether characters typed by the
           user are echoed by getch(3x) as they are typed.   Echoing  by  the  tty
           driver  is  always  disabled,  but  initially getch is in echo mode, so
           characters typed are echoed.  Authors of most interactive programs pre-
           fer  to do their own echoing in a controlled area of the screen, or not
           to echo at all, so  they  disable  echoing  by  calling  noecho.   [See
           curs_getch(3x)  for  a  discussion  of how these routines interact with
           cbreak and nocbreak.]

### halfdelay

           The halfdelay routine is used for half-delay mode, which is similar  to
           cbreak mode in that characters typed by the user are immediately avail-
           able to the program.  However, after blocking for tenths tenths of sec-
           onds,  ERR  is returned if nothing has been typed.  The value of tenths
           must be a number between 1 and 255.  Use nocbreak to  leave  half-delay
           mode.

### intrflush

           If  the  intrflush option is enabled (bf is TRUE), and an interrupt key
           is pressed on the keyboard (interrupt, break, quit), all output in  the
           tty  driver queue will be flushed, giving the effect of faster response
           to the interrupt, but causing curses to have the wrong idea of what  is
           on  the screen.  Disabling the option (bf is FALSE) prevents the flush.
           The default for the option is inherited from the tty  driver  settings.
           The window argument is ignored.

### keypad

           The  keypad  option  enables the keypad of the user's terminal.  If en-
           abled (bf is TRUE), the user can press a function key (such as an arrow
           key)  and  wgetch(3x)  returns a single value representing the function
           key, as in KEY_LEFT.  If disabled (bf is FALSE), curses does not  treat
           function keys specially and the program has to interpret the escape se-
           quences itself.  If the keypad in the terminal can be turned  on  (made
           to  transmit)  and  off  (made to work locally), turning on this option
           causes the terminal keypad to be turned on when wgetch(3x)  is  called.
           The default value for keypad is FALSE.

### meta

           Initially,  whether the terminal returns 7 or 8 significant bits on in-
           put depends on the control mode of the tty driver [see termios(3)].  To
           force  8  bits  to be returned, invoke meta(win, TRUE); this is equiva-
           lent, under POSIX, to setting the CS8 flag on the terminal.  To force 7
           bits to be returned, invoke meta(win, FALSE); this is equivalent, under
           POSIX, to setting the CS7 flag on the terminal.  The  window  argument,
           win, is always ignored.  If the terminfo capabilities smm (meta_on) and
           rmm (meta_off) are defined for the terminal, smm is sent to the  termi-
           nal  when  meta(win,  TRUE)  is  called  and rmm is sent when meta(win,
           FALSE) is called.

### nl/nonl

           The nl and nonl routines control whether the underlying display  device
           translates the return key into newline on input.

### nodelay/notimeout

           The nodelay option causes getch to be a non-blocking call.  If no input
           is ready, getch returns ERR.  If disabled (bf is  FALSE),  getch  waits
           until a key is pressed.

           While  interpreting  an  input escape sequence, wgetch(3x) sets a timer
           while waiting for the  next  character.   If  notimeout(win,  TRUE)  is
           called,  then  wgetch does not set a timer.  The purpose of the timeout
           is to differentiate between sequences received from a function key  and
           those typed by a user.

### raw/noraw

           The  raw and noraw routines place the terminal into or out of raw mode.
           Raw mode is similar to cbreak mode, in that characters typed are  imme-
           diately  passed  through to the user program.  The differences are that
           in raw mode, the interrupt, quit, suspend, and flow control  characters
           are  all  passed through uninterpreted, instead of generating a signal.
           The behavior of the BREAK key depends on other bits in the  tty  driver
           that are not set by curses.

### qiflush/noqiflush

           When  the  noqiflush  routine is used, normal flush of input and output
           queues associated with the INTR, QUIT and SUSP characters will  not  be
           done  [see  termios(3)].   When  qiflush  is called, the queues will be
           flushed when these control characters are read.  You may want  to  call
           noqiflush  in a signal handler if you want output to continue as though
           the interrupt had not occurred, after the handler exits.

### timeout/wtimeout

           The timeout and wtimeout routines set blocking or non-blocking read for
           a  given  window.   If  delay is negative, blocking read is used (i.e.,
           waits indefinitely for input).  If delay  is  zero,  then  non-blocking
           read is used (i.e., read returns ERR if no input is waiting).  If delay
           is positive, then read blocks for delay milliseconds, and  returns  ERR
           if  there  is  still  no input.  Hence, these routines provide the same
           functionality as nodelay, plus the additional capability of being  able
           to block for only delay milliseconds (where delay is positive).

### typeahead

           The curses library does "line-breakout optimization" by looking for ty-
           peahead periodically while updating the screen.  If input is found, and
           it  is  coming  from  a  tty, the current update is postponed until re-
           fresh(3x) or doupdate is called again.  This allows faster response  to
           commands  typed in advance.  Normally, the input FILE pointer passed to
           newterm, or stdin in the case that initscr was used, will be used to do
           this typeahead checking.  The typeahead routine specifies that the file
           descriptor fd is to be used to check for typeahead instead.  If  fd  is
           -1, then no typeahead checking is done.

## RETURN VALUE

           All  routines  that  return  an  integer return ERR upon failure and OK
           (SVr4 specifies only "an integer value other than ERR") upon successful
           completion,  unless  otherwise  noted in the preceding routine descrip-
           tions.

           X/Open does not define any error conditions.  In  this  implementation,
           functions  with  a window parameter will return an error if it is null.
           Any function will also return an error if the terminal was not initial-
           ized.  Also,

                  halfdelay
                       returns  an  error  if  its  parameter is outside the range
                       1..255.

## PORTABILITY

           These functions are described in the XSI Curses standard, Issue 4.

           The ncurses library obeys the XPG4 standard and the historical practice
           of  the  AT&T  curses  implementations, in that the echo bit is cleared
           when curses initializes the terminal state.  BSD curses  differed  from
           this  slightly;  it left the echo bit on at initialization, but the BSD
           raw call turned it off as a side-effect.   For  best  portability,  set
           echo  or noecho explicitly just after initialization, even if your pro-
           gram remains in cooked mode.

           The XSI Curses standard is ambiguous on the  question  of  whether  raw
           should  disable  the  CRLF translations controlled by nl and nonl.  BSD
           curses did turn off these translations; AT&T curses (at least  as  late
           as  SVr1)  did not.  We chose to do so, on the theory that a programmer
           requesting raw input wants a clean  (ideally  8-bit  clean)  connection
           that the operating system will not alter.

           When keypad is first enabled, ncurses loads the key-definitions for the
           current terminal description.  If the terminal description includes ex-
           tended string capabilities, e.g., from using the -x option of tic, then
           ncurses also defines keys for the capabilities whose names  begin  with
           "k".  The corresponding keycodes are generated and (depending on previ-
           ous loads of terminal descriptions) may differ from one execution of  a
           program to the next.  The generated keycodes are recognized by the key-
           name function (which will then return a name beginning with "k"  denot-
           ing  the terminfo capability name rather than "K", used for curses key-
           names).  On the other hand, an application can use define_key to estab-
           lish a specific keycode for a given string.  This makes it possible for
           an application to check for  an  extended  capability's  presence  with
           tigetstr, and reassign the keycode to match its own needs.

           Low-level applications can use tigetstr to obtain the definition of any
           particular string capability.  Higher-level applications which use  the
           curses  wgetch  and  similar functions to return keycodes rely upon the
           order in which the strings are loaded.  If more than one key definition
           has  the  same  string  value, then wgetch can return only one keycode.
           Most curses implementations (including ncurses) load key definitions in
           the  order  defined  by the array of string capability names.  The last
           key to be loaded determines the keycode which  will  be  returned.   In
           ncurses,  you  may  also  have extended capabilities interpreted as key
           definitions.  These are loaded after the predefined keys, and if a  ca-
           pability's value is the same as a previously-loaded key definition, the
           later definition is the one used.

## NOTES

           Note that echo, noecho, halfdelay, intrflush, meta, nl, nonl,  nodelay,
           notimeout, noqiflush, qiflush, timeout, and wtimeout may be macros.

           The  noraw  and  nocbreak calls follow historical practice in that they
           attempt to restore to normal ("cooked") mode from raw and cbreak  modes
           respectively.   Mixing raw/noraw and cbreak/nocbreak calls leads to tty
           driver control states that are hard to predict or understand; it is not
           recommended.

## SEE ALSO

           curses(3x),   curs_getch(3x),   curs_initscr(3x),   curs_util(3x),  de-
           fine_key(3x), termios(3)

                                                                   curs_inopts(3x)