1curs_clear(3X)                                                  curs_clear(3X)
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NAME

6       erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol, wclrtoeol
7       - clear all or part of a curses window
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SYNOPSIS

10       #include <curses.h>
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12       int erase(void);
13       int werase(WINDOW *win);
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15       int clear(void);
16       int wclear(WINDOW *win);
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18       int clrtobot(void);
19       int wclrtobot(WINDOW *win);
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21       int clrtoeol(void);
22       int wclrtoeol(WINDOW *win);
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DESCRIPTION

25   erase/werase
26       The erase and werase routines copy blanks to every position in the win‐
27       dow, clearing the screen.
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29       Blanks created by erasure have the current background rendition (as set
30       by wbkgdset(3X)) merged into them.
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32   clear/wclear
33       The clear and wclear routines are like erase and werase, but they  also
34       call  clearok(3X), so that the screen is cleared completely on the next
35       call to wrefresh for that window and repainted from scratch.
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37   clrtobot/wclrtobot
38       The clrtobot and wclrtobot routines erase from the cursor to the end of
39       screen.   That is, they erase all lines below the cursor in the window.
40       Also, the current line to  the  right  of  the  cursor,  inclusive,  is
41       erased.
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43   clrtoeol/wclrtoeol
44       The clrtoeol and wclrtoeol routines erase the current line to the right
45       of the cursor, inclusive, to the end of the current line.
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RETURN VALUE

48       All routines return the integer OK on success and ERR on failure.
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50       X/Open defines no error conditions.  In this implementation,
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52       •   functions using a window pointer parameter return an error if it is
53           null
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55       •   wclrtoeol returns an error if the cursor position is about to wrap.
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NOTES

58       Note  that  erase, werase, clear, wclear, clrtobot, and clrtoeol may be
59       macros.
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PORTABILITY

62       These functions are described in the XSI Curses standard, Issue 4.  The
63       standard  specifies  that  they return ERR on failure, but specifies no
64       error conditions.
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66       The SVr4.0 manual says that these functions could return  "a  non-nega‐
67       tive  integer  if immedok(3X) is set", referring to the return-value of
68       wrefresh.  In that implementation, wrefresh would return a count of the
69       number of characters written to the terminal.
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71       Some  historic  curses implementations had, as an undocumented feature,
72       the ability to do the equivalent of clearok(..., 1)  by  saying  touch‐
73       win(stdscr) or clear(stdscr).  This will not work under ncurses.
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75       This implementation, and others such as Solaris, sets the current posi‐
76       tion to 0,0 after erasing via werase and wclear.  That fact is not doc‐
77       umented  in  other  implementations, and may not be true of implementa‐
78       tions which were not derived from SVr4 source.
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80       Not obvious from the description, most implementations clear the screen
81       after  wclear  even  for  a subwindow or derived window.  If you do not
82       want to clear the screen during the next wrefresh, use werase instead.
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SEE ALSO

85       curses(3X), curs_outopts(3X), curs_refresh(3X), curs_variables(3X)
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89                                                                curs_clear(3X)
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