ncurses 5.9 - patch 20150214
[ncurses.git] / doc / html / man / curs_clear.3x.html
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36 <TITLE>curs_clear 3x</TITLE>
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41 <H1>curs_clear 3x</H1>
42 <HR>
43 <PRE>
44 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>                                           <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
45
46
47
48
49 </PRE>
50 <H2><a name="h2-NAME">NAME</a></H2><PRE>
51        <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, <STRONG>wclrtobot</STRONG>,
52        <STRONG>clrtoeol</STRONG>, <STRONG>wclrtoeol</STRONG> - clear all or part of a <STRONG>curses</STRONG> window
53
54
55 </PRE>
56 <H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
57        <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
58
59        <STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
60        <STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*win);</STRONG>
61        <STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
62        <STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*win);</STRONG>
63        <STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
64        <STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*win);</STRONG>
65        <STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
66        <STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*win);</STRONG>
67
68
69 </PRE>
70 <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
71        The <STRONG>erase</STRONG> and <STRONG>werase</STRONG> routines copy blanks to  every  posi-
72        tion in the window, clearing the screen.
73
74        The  <STRONG>clear</STRONG>  and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>,
75        but they also call <STRONG>clearok</STRONG>, so that the screen is  cleared
76        completely  on  the  next call to <STRONG>wrefresh</STRONG> for that window
77        and repainted from scratch.
78
79        The <STRONG>clrtobot</STRONG> and <STRONG>wclrtobot</STRONG> routines erase from the  cursor
80        to the end of screen.  That is, they erase all lines below
81        the cursor in the window.  Also, the current line  to  the
82        right of the cursor, inclusive, is erased.
83
84        The <STRONG>clrtoeol</STRONG> and <STRONG>wclrtoeol</STRONG> routines erase the current line
85        to the right of the cursor, inclusive, to the end  of  the
86        current line.
87
88        Blanks created by erasure have the current background ren-
89        dition (as set by <STRONG>wbkgdset</STRONG>) merged into them.
90
91
92 </PRE>
93 <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
94        All routines return the integer <STRONG>OK</STRONG> on success and  <STRONG>ERR</STRONG>  on
95        failure.   The SVr4.0 manual says "or a non-negative inte-
96        ger if <STRONG>immedok</STRONG> is set", but this appears to be an error.
97
98        X/Open defines no error conditions.  In  this  implementa-
99        tion, functions using a window pointer parameter return an
100        error if it is null.
101
102
103 </PRE>
104 <H2><a name="h2-NOTES">NOTES</a></H2><PRE>
105        Note that <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clr-</STRONG>
106        <STRONG>toeol</STRONG> may be macros.
107
108
109 </PRE>
110 <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
111        These  functions are described in the XSI Curses standard,
112        Issue 4.  The standard specifies that they return  <STRONG>ERR</STRONG>  on
113        failure, but specifies no error conditions.
114
115        Some  historic  curses  implementations had, as an undocu-
116        mented feature,  the  ability  to  do  the  equivalent  of
117        <STRONG>clearok(...,</STRONG>  <STRONG>1)</STRONG>  by saying <STRONG>touchwin(stdscr)</STRONG> or <STRONG>clear(std-</STRONG>
118        <STRONG>scr)</STRONG>.  This will not work under ncurses.
119
120        This implementation, and others such as Solaris, sets  the
121        current  position  to  0,0  after erasing via <STRONG>werase()</STRONG> and
122        <STRONG>wclear()</STRONG>.  That fact is not documented in other  implemen-
123        tations, and may not be true of implementations which were
124        not derived from SVr4 source.
125
126        Not obvious from  the  description,  most  implementations
127        clear  the screen after <STRONG>wclear</STRONG> even for a subwindow or de-
128        rived window.  If you do not want to clear the screen dur-
129        ing the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
130
131
132 </PRE>
133 <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
134        <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>curs_vari-</STRONG>
135        <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>
136
137
138
139                                                          <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
140 </PRE>
141 <div class="nav">
142 <ul>
143 <li><a href="#h2-NAME">NAME</a></li>
144 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
145 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
146 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
147 <li><a href="#h2-NOTES">NOTES</a></li>
148 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
149 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
150 </ul>
151 </div>
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