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clear(3ncurses)


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.   The
   SVr4.0  manual  says "or a non-negative integer if immedok is set", but
   this appears to be an error.

   X/Open defines no error conditions.  In this implementation,  functions
   using a window pointer parameter return an error if it is null.

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.

   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)

                                                           clear(3NCURSES)



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