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(3NCURSES) 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(3NCURSES).

       If  no  input  is  pending,  then  if the no-delay flag is set in the window (see nodelay(3NCURSES)), the
       function returns ERR; otherwise, curses waits until the  terminal  has  input.   If  cbreak(3NCURSES)  or
       raw(3NCURSES)  has  been  called,  this  happens  after  one character is read.  If nocbreak(3NCURSES) or
       noraw(3NCURSES) 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(3NCURSES) has been called, curses waits  until  input  is  available  or  the
       specified delay elapses.

       If echo(3NCURSES) 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(3NCURSES)), the cursor
           moves leftward one  position  and  the  new  position  is  erased  as  if  wmove(3NCURSES)  and  then
           wdelch(3NCURSES)  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(3NCURSES).

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

       If  the  wide  character  is a carriage return and nl(3NCURSES) 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(3NCURSES) 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.

NOTES

       See the “NOTES” section of wgetch(3NCURSES).

       All of these functions except wget_wch and unget_wch may be implemented as macros.

       Unlike  wgetch(3NCURSES), 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(3NCURSES).

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(3NCURSES)  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

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

       ncurses(3NCURSES), add_wch(3NCURSES), inopts(3NCURSES), move(3NCURSES), refresh(3NCURSES)

ncurses 6.5                                        2025-08-16                                  get_wch(3NCURSES)