           getch,  wgetch,  mvgetch, mvwgetch, ungetch - 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.

           If noecho has been set, then the character  will  also  be
           echoed into the designated window according to the follow-
           ing rules: If the character is the current  erase  charac-
           ter,  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

           The ungetch routine places ch back onto the input queue to
           be returned by the next call to wgetch.  Note  that  there
           is, in effect, 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).  Keypad is
                                arranged like this:
                                     A1    up    A3
                                    left   B2   right
                                     C1   down   C3
           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_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_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_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

           The has_key routine takes a key value from the above list,
           and  returns TRUE or FALSE according as the current termi-
           nal type recognizes a key with that value.

## 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.

           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-
           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
           feature macro.

## SEE ALSO

           curses(3X),        curs_inopts(3X),         curs_move(3X),
           curs_refresh(3X).