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

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

54       Note  that  erase, werase, clear, wclear, clrtobot, and clrtoeol may be
55       macros.
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PORTABILITY

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

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