# curs_getch 3x

    curs_getch(3x)                                           curs_getch(3x)

## NAME

           getch, wgetch, mvgetch, mvwgetch, ungetch, has_key - get
           (or push back) characters from curses terminal keyboard

## SYNOPSIS

           #include <curses.h>

           int getch(void);
           int wgetch(WINDOW *win);
           int mvgetch(int y, int x);
           int mvwgetch(WINDOW *win, int y, int x);
           int ungetch(int ch);
           int has_key(int ch);

## DESCRIPTION

           The getch, wgetch, mvgetch and mvwgetch, routines  read  a
           character  from the window.  In no-delay mode, if no input
           is waiting, the value ERR is returned.  In delay mode, the
           program  waits until the system passes text through to the
           program.  Depending on the setting of cbreak, this is  af-
           ter  one  character (cbreak mode), or after the first new-
           line (nocbreak mode).  In  half-delay  mode,  the  program
           waits  until a character is typed or the specified timeout
           has been reached.

           Unless noecho has been set, then the character  will  also
           be echoed into the designated window according to the fol-
           lowing rules: if the character is the current erase  char-
           acter,  left  arrow, or backspace, the cursor is moved one
           space to the left and that screen position is erased as if
           delch had been called.  If the character value is any oth-
           er KEY_ define, the user is  alerted  with  a  beep  call.
           Otherwise the character is simply output to the screen.

           If the window is not a pad, and it has been moved or modi-
           fied since the last call to  wrefresh,  wrefresh  will  be
           called before another character is read.

           If  keypad is TRUE, and a function key is pressed, the to-
           ken for that function key is returned instead of  the  raw
           characters.   Possible function keys are defined in <curs-
           es.h> as macros with values outside  the  range  of  8-bit
           characters  whose  names begin with KEY_. Thus, a variable
           intended to hold the return value of a function  key  must
           be of short size or larger.

           When a character that could be the beginning of a function
           key is received (which, on modern terminals, means an  es-
           cape character), curses sets a timer.  If the remainder of
           the sequence does not come in within the designated  time,
           the  character  is passed through; otherwise, the function
           key value is returned.  For this  reason,  many  terminals
           experience a delay between the time a user presses the es-
           cape key and the escape is returned to the program.

           The ungetch routine places ch back onto the input queue to
           be returned by the next call to wgetch.  There is just one
           input queue for all windows.

       Function Keys
           The following function keys, defined in <curses.h>,  might
           be  returned  by  getch  if keypad has been enabled.  Note
           that not all of these are  necessarily  supported  on  any
           particular terminal.

                Name            Key name
                KEY_BREAK       Break key
                KEY_DOWN        The four arrow keys ...
                KEY_UP
                KEY_LEFT
                KEY_RIGHT
                KEY_HOME        Home key (upward+left arrow)
                KEY_BACKSPACE   Backspace
                KEY_F0          Function keys; space for 64 keys
                                is reserved.
                KEY_F(n)        For 0 <= n <= 63
                KEY_DL          Delete line
                KEY_IL          Insert line
                KEY_DC          Delete character
                KEY_IC          Insert char or enter insert mode
                KEY_EIC         Exit insert char mode
                KEY_CLEAR       Clear screen
                KEY_EOS         Clear to end of screen
                KEY_EOL         Clear to end of line
                KEY_SF          Scroll 1 line forward
                KEY_SR          Scroll 1 line backward (reverse)
                KEY_NPAGE       Next page
                KEY_PPAGE       Previous page
                KEY_STAB        Set tab
                KEY_CTAB        Clear tab
                KEY_CATAB       Clear all tabs
                KEY_ENTER       Enter or send
                KEY_SRESET      Soft (partial) reset
                KEY_RESET       Reset or hard reset
                KEY_PRINT       Print or copy
                KEY_LL          Home down or bottom (lower left)
                KEY_A1          Upper left of keypad
                KEY_A3          Upper right of keypad
                KEY_B2          Center of keypad
                KEY_C1          Lower left of keypad
                KEY_C3          Lower right of keypad
                KEY_BTAB        Back tab key
                KEY_BEG         Beg(inning) key
                KEY_CANCEL      Cancel key
                KEY_CLOSE       Close key
                KEY_COMMAND     Cmd (command) key
                KEY_COPY        Copy key
                KEY_CREATE      Create key
                KEY_END         End key
                KEY_EXIT        Exit key
                KEY_FIND        Find key
                KEY_HELP        Help key
                KEY_MARK        Mark key
                KEY_MESSAGE     Message key
                KEY_MOUSE       Mouse event read
                KEY_MOVE        Move key
                KEY_NEXT        Next object key
                KEY_OPEN        Open key
                KEY_OPTIONS     Options key
                KEY_PREVIOUS    Previous object key
                KEY_REDO        Redo key
                KEY_REFERENCE   Ref(erence) key
                KEY_REFRESH     Refresh key
                KEY_REPLACE     Replace key
                KEY_RESIZE      Screen resized
                KEY_RESTART     Restart key
                KEY_RESUME      Resume key

                KEY_SAVE        Save key
                KEY_SBEG        Shifted beginning key
                KEY_SCANCEL     Shifted cancel key
                KEY_SCOMMAND    Shifted command key
                KEY_SCOPY       Shifted copy key
                KEY_SCREATE     Shifted create key
                KEY_SDC         Shifted delete char key
                KEY_SDL         Shifted delete line key
                KEY_SELECT      Select key
                KEY_SEND        Shifted end key
                KEY_SEOL        Shifted clear line key
                KEY_SEXIT       Shifted exit key
                KEY_SFIND       Shifted find key
                KEY_SHELP       Shifted help key
                KEY_SHOME       Shifted home key
                KEY_SIC         Shifted input key
                KEY_SLEFT       Shifted left arrow key
                KEY_SMESSAGE    Shifted message key
                KEY_SMOVE       Shifted move key
                KEY_SNEXT       Shifted next key
                KEY_SOPTIONS    Shifted options key
                KEY_SPREVIOUS   Shifted prev key
                KEY_SPRINT      Shifted print key
                KEY_SREDO       Shifted redo key
                KEY_SREPLACE    Shifted replace key
                KEY_SRIGHT      Shifted right arrow
                KEY_SRSUME      Shifted resume key
                KEY_SSAVE       Shifted save key
                KEY_SSUSPEND    Shifted suspend key
                KEY_SUNDO       Shifted undo key
                KEY_SUSPEND     Suspend key
                KEY_UNDO        Undo key

           Keypad is arranged like this:

                             +-----+------+-------+
                             | A1  |  up  |  A3   |
                             +-----+------+-------+
                             |left |  B2  | right |
                             +-----+------+-------+
                             | C1  | down |  C3   |
                             +-----+------+-------+
           The has_key routine takes a key value from the above list,
           and returns TRUE or FALSE according to whether the current
           terminal type recognizes a key with that value.  Note that
           a  few  values  do  not  correspond  to  a real key, e.g.,
           KEY_RESIZE and KEY_MOUSE.  See resizeterm(3x) for more de-
           tails  about  KEY_RESIZE, and curs_mouse(3x) for a discus-
           sion of KEY_MOUSE.

## RETURN VALUE

           All routines return the integer ERR upon  failure  and  an
           integer value other than ERR (OK in the case of ungetch())
           upon successful completion.

                  ungetch
                       returns an error if there is no more  room  in
                       the FIFO.

                  wgetch
                       returns  an  error  if  the  window pointer is
                       null, or if its timeout expires without having
                       any data.

           Functions  with a "mv" prefix first perform a cursor move-
           ment using wmove, and return an error if the  position  is
           outside the window, or if the window pointer is null.

## NOTES

           Use of the escape key by a programmer for a single charac-
           ter function is discouraged, as it will cause a  delay  of
           up to one second while the keypad code looks for a follow-
           ing function-key sequence.

           Note that some keys may be the same as commonly used  con-
           trol keys, e.g., KEY_ENTER versus control/M, KEY_BACKSPACE
           versus control/H.  Some curses implementations may  differ
           according  to  whether  they treat these control keys spe-
           cially (and ignore the terminfo), or use the terminfo def-
           initions.   Ncurses  uses  the terminfo definition.  If it
           says  that  KEY_ENTER  is  control/M,  getch  will  return
           KEY_ENTER when you press control/M.

           Generally,  KEY_ENTER denotes the character(s) sent by the
           Enter key on the numeric keypad:

           o   the terminal description lists the most useful keys,

           o   the Enter key on the regular keyboard is already  han-
               dled by the standard ASCII characters for carriage-re-
               turn and line-feed,

           o   depending on whether nl or nonl was  called,  pressing
               "Enter"  on  the  regular keyboard may return either a
               carriage-return or line-feed, and finally

           o   "Enter or send" is the standard description  for  this
               key.

           When  using  getch, wgetch, mvgetch, or mvwgetch, nocbreak
           mode (nocbreak) and echo mode (echo) should not be used at
           the  same  time.  Depending on the state of the tty driver
           when each character is typed, the program may produce  un-
           desirable results.

           Note that getch, mvgetch, and mvwgetch may be macros.

           Historically, the set of keypad macros was largely defined
           by the extremely function-key-rich keyboard  of  the  AT&T
           7300,  aka  3B1,  aka Safari 4.  Modern personal computers
           usually have only a small subset of these.   IBM  PC-style
           consoles   typically  support  little  more  than  KEY_UP,
           KEY_DOWN,   KEY_LEFT,   KEY_RIGHT,   KEY_HOME,    KEY_END,
           KEY_NPAGE, KEY_PPAGE, and function keys 1 through 12.  The
           Ins key is usually mapped to KEY_IC.

## PORTABILITY

           The *get* functions are described in the XSI Curses  stan-
           dard,  Issue  4.   They  read single-byte characters only.
           The standard specifies that they return  ERR  on  failure,
           but specifies no error conditions.

           The  echo  behavior of these functions on input of KEY_ or
           backspace characters was not specified in the  SVr4  docu-
           mentation.  This description is adopted from the XSI Curs-
           es standard.

           The behavior of getch and friends in the presence of  han-
           dled  signals  is  unspecified  in the SVr4 and XSI Curses
           documentation.  Under historical  curses  implementations,
           it  varied depending on whether the operating system's im-
           plementation  of  handled  signal  receipt  interrupts   a
           read(2)  call in progress or not, and also (in some imple-
           mentations) depending on whether an input timeout or  non-
           blocking mode has been set.

           Programmers concerned about portability should be prepared
           for either of two cases: (a) signal receipt does  not  in-
           terrupt  getch;  (b)  signal  receipt interrupts getch and
           causes it to return ERR with errno set  to  EINTR.   Under
           the  ncurses  implementation, handled signals never inter-
           rupt getch.

           The has_key function is unique to ncurses.   We  recommend
           that  any  code  using it be conditionalized on the NCURS-
           ES_VERSION feature macro.

## SEE ALSO

           curses(3x),       curs_inopts(3x),       curs_outopts(3x),
           curs_mouse(3x),   curs_move(3x),   curs_refresh(3x),   re-
           sizeterm(3x).

           Comparable functions in the wide-character (ncursesw)  li-
           brary are described in curs_get_wch(3x).

                                                             curs_getch(3x)