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NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

       #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    [Toc]    [Back]

       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 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    [Toc]    [Back]
       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_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.

RETURN VALUE    [Toc]    [Back]

       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    [Toc]    [Back]

       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

       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_PPAGE, and function keys 1 through 12.   The  Ins  key  is  usually
       mapped to KEY_IC.

PORTABILITY    [Toc]    [Back]

       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 standard.

       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 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 interrupt

       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    [Toc]    [Back]

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

[ Back ]
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