curs_get_wch(3x) — Linux manual page


curs_get_wch(3X)                                        curs_get_wch(3X)

NAME         top

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

SYNOPSIS         top

       #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         top

       The get_wch, wget_wch, mvget_wch, and mvwget_wch functions read a
       character from the terminal associated with the current or
       specified 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 the user types a character or the specified
       timeout interval has elapsed.

       Unless noecho has been set, these routines echo the character
       into the designated window.

       If the window is not a pad and has been moved or modified since
       the last call to wrefresh, wrefresh will be called before another
       character is read.

       If keypad is enabled, these functions respond to the pressing of
       a function key by setting the object pointed to by wch to the
       keycode assigned to the function key, and returning KEY_CODE_YES.
       If a character (such as escape) that could be the beginning of a
       function key is received, curses sets a timer.  If the remainder
       of the sequence does arrive within the designated time, curses
       passes through the character; otherwise, curses returns the
       function key value.  For this reason, many terminals experience a
       delay between the time a user presses the escape key and the time
       the escape is returned to the program.

       The keycodes returned by these functions are the same as those
       returned by wgetch:

       •   The predefined function keys are listed in <curses.h> as
           macros with values outside the range of 8-bit characters.
           Their names begin with KEY_.

       •   Other (user-defined) function keys which may be defined using
           define_key(3X) have no names, but also are expected to have
           values outside the range of 8-bit characters.

       The unget_wch function pushes the wide character wch back onto
       the head of the input queue, so the wide character is returned by
       the next call to get_wch.  The pushback of one character is
       guaranteed.  If the program calls unget_wch too many times
       without an intervening call to get_wch, the operation may fail.

       Unlike ungetch and wgetch, unget_wch cannot distinguish special
       characters returned by wget_wch from ordinary characters.  An
       application can push special keys which it may read via wget_wch
       by checking for the KEY_CODE_YES result, and using ungetch for
       those special keys.

NOTES         top

       The header file <curses.h> automatically includes the header file

       Applications should not define the escape key by itself as a
       single-character function.

       When using get_wch, wget_wch, mvget_wch, or mvwget_wch,
       applications should not use nocbreak mode and echo mode at the
       same time.  Depending on the state of the tty driver when each
       character is typed, the program may produce undesirable results.

       All functions except wget_wch and unget_wch may be macros.

RETURN VALUE         top

       When get_wch, wget_wch, mvget_wch, and mvwget_wch functions
       successfully report the pressing of a function key, they return
       KEY_CODE_YES.  When they successfully report a wide character,
       they return OK.  Otherwise, they return ERR.

       Upon successful completion, unget_wch returns OK.  Otherwise, the
       function returns ERR.

       Functions with a “mv” prefix first perform a cursor movement
       using wmove, and return an error if the position is outside the
       window, or if the window pointer is null.

SEE ALSO         top

       curses(3X), curs_getch(3X), curs_ins_wch(3X), curs_inopts(3X),
       curs_move(3X), curs_refresh(3X)

COLOPHON         top

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