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 "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 6.6                       2025-08-16                  curs_get_wch(3X)