curs_get_wch(3x) Library calls curs_get_wch(3x)
get_wch, wget_wch, mvget_wch, mvwget_wch, unget_wch - get (or push
back) a wide character from curses terminal keyboard
#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);
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) 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 normal 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,
wgetch stores the the wide character code for line feed in wch instead.
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 terminal.
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 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 if there is no more room in the
input queue.
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 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.
See the "EXTENSIONS" section of wgetch(3x).
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.
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 2024-06-08 curs_get_wch(3x)