Provided by: ncurses-doc_5.9-4_all bug


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


       #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);


       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 newline
       (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 following rules: if the character is the current erase  character,
       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  modified  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

       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

                            Name            Key name
                            KEY_BREAK       Break key
                            KEY_DOWN        The four arrow keys ...
                            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:

                                         │ A1upA3   │
                                         │leftB2right │
                                         │ C1downC3   │
       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(3NCURSES)  for  more  details  about  KEY_RESIZE,  and  mouse(3NCURSES)  for  a
       discussion of KEY_MOUSE.


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

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

                   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 movement using wmove,  and  return  an
       error if the position is outside the window, or if the window pointer is null.


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

       Note  that some keys may be the same as commonly used control 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 specially (and ignore the terminfo), or
       use the terminfo definitions.  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:

       ·   the terminal description lists the most useful keys,

       ·   the  Enter  key  on  the  regular  keyboard  is  already handled by the standard ASCII
           characters for carriage-return and line-feed,

       ·   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

       ·   "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 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
       function keys 1 through 12.  The Ins key is usually mapped to KEY_IC.


       The  *get* functions are described in the XSI Curses standard, 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 documentation.  This description is  adopted  from  the  XSI  Curses

       The behavior of getch and friends in the presence of handled 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 implementations) 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 interrupt getch.

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


       ncurses(3NCURSES),  inopts(3NCURSES),  outopts(3NCURSES), mouse(3NCURSES), move(3NCURSES),
       refresh(3NCURSES), resizeterm(3NCURSES).

       Comparable  functions  in  the  wide-character  (ncursesw)  library   are   described   in