NAME

       erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol, wclrtoeol - clear all or part of a curses
       window

SYNOPSIS

       #include <curses.h>

       int erase(void);
       int werase(WINDOW *win);

       int clear(void);
       int wclear(WINDOW *win);

       int clrtobot(void);
       int wclrtobot(WINDOW *win);

       int clrtoeol(void);
       int wclrtoeol(WINDOW *win);

DESCRIPTION

       The erase and werase routines copy blanks to every position in the window, clearing the screen.

       The  clear  and wclear routines are like erase and werase, but they also call clearok, so that the screen
       is cleared completely on the next call to wrefresh for that window and repainted from scratch.

       The clrtobot and wclrtobot routines erase from the cursor to the end of screen.  That is, they erase  all
       lines  below  the cursor in the window.  Also, the current line to the right of the cursor, inclusive, is
       erased.

       The clrtoeol and wclrtoeol routines erase the current line to the right of the cursor, inclusive, to  the
       end of the current line.

       Blanks created by erasure have the current background rendition (as set by wbkgdset) merged into them.

RETURN VALUE

       All routines return the integer OK on success and ERR on failure.

       X/Open defines no error conditions.  In this implementation,

       •   functions using a window pointer parameter return an error if it is null

       •   wclrtoeol returns an error if the cursor position is about to wrap.

NOTES

       Note that erase, werase, clear, wclear, clrtobot, and clrtoeol may be macros.

PORTABILITY

       These  functions are described in the XSI Curses standard, Issue 4.  The standard specifies that they re‐
       turn ERR on failure, but specifies no error conditions.

       The SVr4.0 manual says that these functions could return "a non-negative integer if immedok is set",  re‐
       ferring  to  the  return-value of wrefresh.  In that implementation, wrefresh would return a count of the
       number of characters written to the terminal.

       Some historic curses implementations had, as an undocumented feature, the ability to do the equivalent of
       clearok(..., 1) by saying touchwin(stdscr) or clear(stdscr).  This will not work under ncurses.

       This implementation, and others such as Solaris, sets the current  position  to  0,0  after  erasing  via
       werase  and  wclear.  That fact is not documented in other implementations, and may not be true of imple‐
       mentations which were not derived from SVr4 source.

       Not obvious from the description, most implementations clear the screen after wclear even for a subwindow
       or derived window.  If you do not want to clear the screen during the next wrefresh, use werase instead.

SEE ALSO

       ncurses(3NCURSES), outopts(3NCURSES), refresh(3NCURSES), curses_variables(3NCURSES)

                                                                                                 clear(3NCURSES)