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curs_get_wch 3x 2024-03-23 ncurses 6.4 Library calls

curs_get_wch(3x)                 Library calls                curs_get_wch(3x)




NAME

       get_wch,  wget_wch,  mvget_wch,  mvwget_wch,  unget_wch  - get (or push
       back) a wide character from curses terminal keyboard


SYNOPSIS

       #include <curses.h>

       int get_wch(wint_t *wch);
       int wget_wch(WINDOW *win, wint_t *wch);
       int mvget_wch(int y, int x, wint_t *wch);
       int mvwget_wch(WINDOW *win, int y, int x, wint_t *wch);

       int unget_wch(const wchar_t wch);


DESCRIPTION


Reading Characters

       wget_wch gathers a key stroke wch from the terminal keyboard associated
       with  a  curses  window  win, returning OK if a wide character is read,
       KEY_CODE_YES if a function key is read, and ERR  if  no  key  event  is
       available.  ncurses(3x) describes the variants of this function.

       When  input  is pending, wget_wch stores an integer identifying the key
       stroke in wch;  for  alphanumeric  and  punctuation  keys,  this  value
       corresponds to the character encoding used by the terminal.  Use of the
       control key as a modifier  often  results  in  a  distinct  code.   The
       behavior  of  other  keys depends on whether win is in keypad mode; see
       subsections "Keypad Mode" and "Predefined Key Codes" in getch(3x).

       If no input is pending, then if the no-delay flag is set in the  window
       (see  nodelay(3x)),  the  function returns ERR; otherwise, curses waits
       until the terminal has input.  If  cbreak(3x)  has  been  called,  this
       happens  after one character is read.  If nocbreak(3x) has been called,
       it occurs when the next newline is read.   If  halfdelay(3x)  has  been
       called,  curses waits until a character is typed or the specified delay
       elapses.

       If echo(3x) has been called, and the window is not a pad, curses writes
       wch to the window (at the cursor position) per the following rules.

       o   If  wch  matches  the  terminal's erase character, the cursor moves
           leftward one  position  and  the  new  position  is  erased  as  if
           wmove(3x)  and  then  wdelch(3x)  were  called.   When the window's
           keypad mode is enabled (see below), KEY_LEFT and KEY_BACKSPACE  are
           handled the same way.

       o   curses writes any other wch to the window, as with wecho_wchar(3x).

       o   If  the  window  has  been moved or modified since the last call to
           wrefresh(3x), curses calls wrefresh.

       If wch is a carriage return and nl(3x) has been called,  wgetch  stores
       the the character code for newline (line feed) in wch instead.


Ungetting Characters

       unget_wch  places  wch  into the input queue to be returned by the next
       call to wget_wch.  A single input queue serves all windows.


RETURN VALUE

       wget_wch returns OK when it reads a  wide  character  and  KEY_CODE_YES
       when it reads a function key code.  It returns ERR if

       o   the WINDOW pointer is NULL, or

       o   its timeout expires without any data arriving, or

       o   execution  was  interrupted by a signal, in which case errno is set
           to EINTR.

       Functions with a  "mv"  prefix  first  perform  cursor  movement  using
       wmove(3x) and fail if the position is outside the window, or (for "mvw"
       functions) if the win parameter is a null pointer.

       unget_wch returns OK on success and ERR if there is no more room in the
       input queue.


NOTES

       See the "NOTES" section of wgetch(3x).

       All of these functions except wget_wch and unget_wch may be implemented
       as macros.

       Unlike wgetch(3x), wget_wch and its variants store  the  value  of  the
       input  character  in  an additional wch parameter instead of the return
       value.

       Unlike  ungetch,  unget_wch  cannot  distinguish  function  key   codes
       wget_wch   from  conventional  character  codes.   An  application  can
       overcome this limitation by pushing function key codes with ungetch and
       subsequently  checking  the  return  value of wget_wch for a match with
       KEY_CODE_YES.


EXTENSIONS

       See the "EXTENSIONS" section of wgetch(3x).


PORTABILITY

       Applications employing ncurses extensions should condition their use on
       the visibility of the NCURSES_VERSION preprocessor macro.

       X/Open  Curses,  Issue  4,  describes these functions.  It specifies no
       error conditions for them.

       See the "PORTABILITY" section of wgetch(3x) regarding  the  interaction
       of wget_wch with signal handlers.


SEE ALSO

       curses(3x),     curs_add_wch(3x),    curs_inopts(3x),    curs_move(3x),
       curs_refresh(3x)

       curs_getch(3x) describes comparable functions of the ncurses library in
       its non-wide-character configuration.



ncurses 6.4                       2024-03-23                  curs_get_wch(3x)