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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

       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    [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 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_NPAGE, 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  nonblocking
 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(3),  curs_inopts(3),  curs_mouse(3),  curs_move(3),
       curs_refresh(3).  resizeterm(3).
[ Back ]
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