# curs_get_wch 3x 2025-04-05 ncurses 6.5 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 buffer

## 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 wc);

## DESCRIPTION

### Reading Characters

           wget_wch gathers a key event 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
           event 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,  by  holding  it  down  while  pressing  and
           releasing  another key, 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)  or raw(3x) has been
           called, this happens after one character is read.  If  nocbreak(3x)  or
           noraw(3x)  has  been  called,  it occurs when the next newline is read.
           (Because the terminal's canonical or "cooked"  mode  is  line-buffered,
           multiple  wget_wch  calls  may  then  be  necessary  to empty the input
           queue.)  If halfdelay(3x) has been called, curses waits until input  is
           available or the specified delay elapses.

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

           o   If  the  wide character matches the terminal's erase character (see
               erasewchar(3x)), 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  wide  character  to the window, as with
               wecho_wchar(3x).

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

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

### Ungetting Characters

           unget_wch places wc into the input queue to be retrieved  by  the  next
           call  to  wget_wch.  A single input queue serves all windows associated
           with the screen.

## RETURN VALUE

           wget_wch returns OK when it reads a wide character,  KEY_CODE_YES  when
           it  reads  a  function key code, and ERR on failure.  wget_wch fails if
           its timeout expires without any data arriving, which cannot  happen  if
           nodelay(3x) is in effect on the window.

           In ncurses, wget_wch also fails if

           o   the curses screen has not been initialized,

           o   (for  functions  taking  a  WINDOW  pointer argument) win is a null
               pointer, or

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

           Functions  prefixed with "mv" first perform cursor movement and fail if
           the position (y, x) is outside the window boundaries.

           unget_wch returns OK on  success  and  ERR  on  failure.   In  ncurses,
           unget_wch fails if

           o   the curses screen has not been initialized, or

           o   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 stores 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 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.

## HISTORY

           X/Open  Curses Issue 4 (1995) initially specified these functions.  The
           System V Interface Definition Version 4  of  the  same  year  specified
           functions named wgetwch (with its variants) ungetwch.  These were later
           additions to SVr4.x, not appearing in  the  first  SVr4  (1989).   They
           differ from X/Open's later wget_wch and unget_wch in that wgetwch takes
           no wch argument, but returns the (wide) key code as  an  int  (with  no
           provision  for  distinguishing  a  character  code  from a function key
           code); and ungetwch takes a non-const int argument.

## SEE ALSO

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

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

    ncurses 6.5                       2025-04-05                  curs_get_wch(3x)