curs_clear 3x

curs_clear(3x)                                                  curs_clear(3x)

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 win-
       dow, 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,

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

       o   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-nega-
       tive  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  touch-
       win(stdscr) or clear(stdscr).  This will not work under ncurses.

       This implementation, and others such as Solaris, sets the current posi-
       tion to 0,0 after erasing via werase and wclear.  That fact is not doc-
       umented  in  other  implementations, and may not be true of implementa-
       tions 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.