# 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
           after 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
           other 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
           token for that function key is returned instead of the raw
           characters.    Possible   function  keys  are  defined  in
           <curses.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
           escape  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 escape 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.

## 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.

## 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.

           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
           undesirable 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
           Curses 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
           implementation 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
           interrupt  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
           NCURSES_VERSION feature macro.

## SEE ALSO

           curses(3x),        curs_inopts(3x),        curs_mouse(3x),
           curs_move(3x), curs_refresh(3x).  resizeterm(3x).

                                                       curs_getch(3x)