ncurses 6.1 - patch 20191130
[ncurses.git] / doc / html / man / curs_clear.3x.html
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41 <H1 class="no-header">curs_clear 3x</H1>
42 <PRE>
43 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>                                                  <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
44
45
46
47
48 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
49        <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, <STRONG>wclrtobot</STRONG>, <STRONG>clrtoeol</STRONG>, <STRONG>wclrtoeol</STRONG>
50        - clear all or part of a <STRONG>curses</STRONG> window
51
52
53 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
54        <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
55
56        <STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
57        <STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*win);</STRONG>
58        <STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
59        <STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*win);</STRONG>
60        <STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
61        <STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*win);</STRONG>
62        <STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
63        <STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*win);</STRONG>
64
65
66 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
67        The <STRONG>erase</STRONG> and <STRONG>werase</STRONG> routines copy blanks to every position in the win-
68        dow, clearing the screen.
69
70        The  <STRONG>clear</STRONG> and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>, but they also
71        call <STRONG>clearok</STRONG>, so that the screen is cleared completely on the next call
72        to <STRONG>wrefresh</STRONG> for that window and repainted from scratch.
73
74        The <STRONG>clrtobot</STRONG> and <STRONG>wclrtobot</STRONG> routines erase from the cursor to the end of
75        screen.  That is, they erase all lines below the cursor in the  window.
76        Also,  the  current  line  to  the  right  of the cursor, inclusive, is
77        erased.
78
79        The <STRONG>clrtoeol</STRONG> and <STRONG>wclrtoeol</STRONG> routines erase the current line to the right
80        of the cursor, inclusive, to the end of the current line.
81
82        Blanks created by erasure have the current background rendition (as set
83        by <STRONG>wbkgdset</STRONG>) merged into them.
84
85
86 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
87        All routines return the integer <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.   The
88        SVr4.0  manual  says "or a non-negative integer if <STRONG>immedok</STRONG> is set", but
89        this appears to be an error.
90
91        X/Open defines no error conditions.  In this implementation,  functions
92        using a window pointer parameter return an error if it is null.
93
94
95 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
96        Note  that  <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clrtoeol</STRONG> may be
97        macros.
98
99
100 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
101        These functions are described in the XSI Curses standard, Issue 4.  The
102        standard  specifies  that  they return <STRONG>ERR</STRONG> on failure, but specifies no
103        error conditions.
104
105        Some historic curses implementations had, as an  undocumented  feature,
106        the  ability  to  do the equivalent of <STRONG>clearok(...,</STRONG> <STRONG>1)</STRONG> by saying <STRONG>touch-</STRONG>
107        <STRONG>win(stdscr)</STRONG> or <STRONG>clear(stdscr)</STRONG>.  This will not work under ncurses.
108
109        This implementation, and others such as Solaris, sets the current posi-
110        tion to 0,0 after erasing via <STRONG>werase</STRONG> and <STRONG>wclear</STRONG>.  That fact is not doc-
111        umented in other implementations, and may not be  true  of  implementa-
112        tions which were not derived from SVr4 source.
113
114        Not obvious from the description, most implementations clear the screen
115        after <STRONG>wclear</STRONG> even for a subwindow or derived window.   If  you  do  not
116        want to clear the screen during the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
117
118
119 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
120        <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
121
122
123
124                                                                 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
125 </PRE>
126 <div class="nav">
127 <ul>
128 <li><a href="#h2-NAME">NAME</a></li>
129 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
130 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
131 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
132 <li><a href="#h2-NOTES">NOTES</a></li>
133 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
134 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
135 </ul>
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