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.

       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  SVr4.0  manual  says  that these functions could return “or a non-negative integer if
       immedok is set”, referring 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 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)