Manual Pages  — curs_get_wch

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

SYNOPSIS DESCRIPTION Reading Characters Ungetting Characters RETURN VALUE NOTES EXTENSIONS PORTABILITY SEE ALSO

#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 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(3X) 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(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) has been called, it occurs when the next newline is read. If  halfdelay(3X) has been called, curses waits until a character is typed or the specified delay elapses.

If  echo(3X) 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(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 wch to the window, as with  wecho_wchar(3X).
»	If the window has been moved or modified since the last call to  wrefresh(3X), curses calls  wrefresh.

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

 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.

 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.

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  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.

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)