NAME

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

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 stroke wch 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 stroke 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 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(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) has been
       called,  this happens after one character is read.  If nocbreak(3NCURSES) has been called, it occurs when
       the next newline is read.  If halfdelay(3NCURSES) has been called, curses  waits  until  a  character  is
       typed or the specified delay elapses.

       If  echo(3NCURSES)  has been called, and the window is not a pad, curses writes wch to the window (at the
       cursor position) per the following rules.

       •   If wch matches the terminal's erase character, 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 wch to the window, as with wecho_wchar(3NCURSES).

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

       If  wch  is  a carriage return and nl(3NCURSES) has been called, wgetch stores the the character code for
       newline (line feed) in wch instead.

   Ungetting Characters
       unget_wch places wch into the input queue to be returned by the next call to wget_wch.   A  single  input
       queue serves all windows.

RETURN VALUE

       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

       •   the WINDOW pointer is NULL, or

       •   its timeout expires without any data arriving, 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 if 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 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 wget_wch 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.

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                                        2024-04-20                                  get_wch(3NCURSES)