# 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.  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).
               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 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.

           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 hsd 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).