ncurses 6.0 - patch 20170401
[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>,
50        <STRONG>clrtoeol</STRONG>, <STRONG>wclrtoeol</STRONG> - 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  posi-
68        tion in the window, clearing the screen.
69
70        The  <STRONG>clear</STRONG>  and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>,
71        but they also call <STRONG>clearok</STRONG>, so that the screen is  cleared
72        completely  on  the  next call to <STRONG>wrefresh</STRONG> for that window
73        and repainted from scratch.
74
75        The <STRONG>clrtobot</STRONG> and <STRONG>wclrtobot</STRONG> routines erase from the  cursor
76        to the end of screen.  That is, they erase all lines below
77        the cursor in the window.  Also, the current line  to  the
78        right of the cursor, inclusive, is erased.
79
80        The <STRONG>clrtoeol</STRONG> and <STRONG>wclrtoeol</STRONG> routines erase the current line
81        to the right of the cursor, inclusive, to the end  of  the
82        current line.
83
84        Blanks created by erasure have the current background ren-
85        dition (as set by <STRONG>wbkgdset</STRONG>) merged into them.
86
87
88 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
89        All routines return the integer <STRONG>OK</STRONG> on success and  <STRONG>ERR</STRONG>  on
90        failure.   The SVr4.0 manual says "or a non-negative inte-
91        ger if <STRONG>immedok</STRONG> is set", but this appears to be an error.
92
93        X/Open defines no error conditions.  In  this  implementa-
94        tion, functions using a window pointer parameter return an
95        error if it is null.
96
97
98 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
99        Note that <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clr-</STRONG>
100        <STRONG>toeol</STRONG> may be macros.
101
102
103 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
104        These  functions are described in the XSI Curses standard,
105        Issue 4.  The standard specifies that they return  <STRONG>ERR</STRONG>  on
106        failure, but specifies no error conditions.
107
108        Some  historic  curses  implementations had, as an undocu-
109        mented feature,  the  ability  to  do  the  equivalent  of
110        <STRONG>clearok(...,</STRONG>  <STRONG>1)</STRONG>  by saying <STRONG>touchwin(stdscr)</STRONG> or <STRONG>clear(std-</STRONG>
111        <STRONG>scr)</STRONG>.  This will not work under ncurses.
112
113        This implementation, and others such as Solaris, sets  the
114        current  position  to  0,0  after  erasing  via <STRONG>werase</STRONG> and
115        <STRONG>wclear</STRONG>.  That fact is not documented in other  implementa-
116        tions,  and  may not be true of implementations which were
117        not derived from SVr4 source.
118
119        Not obvious from  the  description,  most  implementations
120        clear  the screen after <STRONG>wclear</STRONG> even for a subwindow or de-
121        rived window.  If you do not want to clear the screen dur-
122        ing the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
123
124
125 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
126        <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>
127        <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>
128
129
130
131                                                          <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
132 </PRE>
133 <div class="nav">
134 <ul>
135 <li><a href="#h2-NAME">NAME</a></li>
136 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
137 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
138 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
139 <li><a href="#h2-NOTES">NOTES</a></li>
140 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
141 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
142 </ul>
143 </div>
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