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

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

       Blanks created by erasure have the current background rendition (as  set  by  wbkgdset(3NCURSES))  merged
       into them.

   clear, wclear
       The  clear  and  wclear routines are like erase and werase, but they also call clearok(3NCURSES), so that
       the screen is cleared completely on the next call to wrefresh for that window and repainted from scratch.

   clrtobot, wclrtobot
       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.

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

RETURN VALUE

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

       In this implementation,

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

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

NOTES

       erase, werase, clear, wclear, clrtobot, and clrtoeol may be implemented as macros.

PORTABILITY

       X/Open Curses Issue 4 describes these functions.  It specifies no error conditions for them.

       SVr4  documentation  says that these functions return OK “or a non-negative integer if immedok() is set”,
       referring to the return value from wrefresh, which in SVr4 returns a count of characters written  to  the
       window if its immedok property is set; in ncurses, it does not.

       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
       implementations 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)

ncurses 6.5                                        2025-01-18                                    clear(3NCURSES)