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(3X))
       merged into them.

   clear/wclear
       The clear and wclear routines are like erase and werase, but they also  call  clearok(3X),
       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 standard specifies
       that they return ERR on failure, but specifies no error conditions.

       The SVr4.0 manual says that these  functions  could  return  "a  non-negative  integer  if
       immedok(3X)  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)