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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXTENSIONS | PORTABILITY | HISTORY | SEE ALSO | COLOPHON |
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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 buffer
#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);
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.
• 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.
• curses writes any other wide character to the window, as with
wecho_wchar(3X).
• 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.
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
• the curses screen has not been initialized,
• (for functions taking a WINDOW pointer argument) win is a null
pointer, or
• 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
• the curses screen has not been initialized, or
• 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 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.
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.
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.
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)
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://invisible-island.net/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to bug-ncurses@gnu.org.
This page was obtained from the tarball ncurses-6.6.tar.gz fetched
from ⟨https://ftp.gnu.org/gnu/ncurses/⟩ on 2026-01-16. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for the
page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
ncurses @NCURSES_MAJOR@.@NCU... 2025-08-16 curs_get_wch(3X)
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HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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