ncurses 5.7 - patch 20100731
[ncurses.git] / doc / html / man / curs_clear.3x.html
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+  * @Id: curs_clear.3x,v 1.12 2010/07/31 16:12:01 tom Exp @
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 <HTML>
+<HEAD>
+<TITLE>curs_clear 3x</TITLE>
+<link rev=made href="mailto:bug-ncurses@gnu.org">
+<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
+</HEAD>
 <BODY>
+<H1>curs_clear 3x</H1>
+<HR>
 <PRE>
 <!-- Manpage converted by man2html 3.0.1 -->
+<STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>                                           <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
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 </PRE>
 <H2>NAME</H2><PRE>
-       <B>erase</B>,  <B>werase</B>,  <B>clear</B>,  <B>wclear</B>, <B>clrtobot</B>, <B>wclrtobot</B>, <B>clr-</B>
-       <B>toeol</B>, <B>wclrtoeol</B> - clear all or part of a <B>curses</B> window
+       <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, <STRONG>wclrtobot</STRONG>,
+       <STRONG>clrtoeol</STRONG>, <STRONG>wclrtoeol</STRONG> - clear all or part of a <STRONG>curses</STRONG> window
 
 
 </PRE>
 <H2>SYNOPSIS</H2><PRE>
-       <B>#</B> <B>include</B> <B>&lt;curses.h&gt;</B>
+       <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
 
-       <B>int</B> <B>erase(void);</B>
-       <B>int</B> <B>werase(WINDOW</B> <B>*win);</B>
-       <B>int</B> <B>clear(void);</B>
-       <B>int</B> <B>wclear(WINDOW</B> <B>*win);</B>
-       <B>int</B> <B>clrtobot(void);</B>
-       <B>int</B> <B>wclrtobot(WINDOW</B> <B>*win);</B>
-       <B>int</B> <B>clrtoeol(void);</B>
-       <B>int</B> <B>wclrtoeol(WINDOW</B> <B>*win);</B>
+       <STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
+       <STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*win);</STRONG>
+       <STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
+       <STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*win);</STRONG>
+       <STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
+       <STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*win);</STRONG>
+       <STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
+       <STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*win);</STRONG>
 
 
 </PRE>
 <H2>DESCRIPTION</H2><PRE>
-       The <B>erase</B> and <B>werase</B> routines copy blanks to  every  posi-
+       The <STRONG>erase</STRONG> and <STRONG>werase</STRONG> routines copy blanks to  every  posi-
        tion in the window, clearing the screen.
 
-       The  <B>clear</B>  and <B>wclear</B> routines are like <B>erase</B> and <B>werase</B>,
-       but they also call <B>clearok</B>, so that the screen is  cleared
-       completely  on  the  next call to <B>wrefresh</B> for that window
+       The  <STRONG>clear</STRONG>  and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>,
+       but they also call <STRONG>clearok</STRONG>, so that the screen is  cleared
+       completely  on  the  next call to <STRONG>wrefresh</STRONG> for that window
        and repainted from scratch.
 
-       The <B>clrtobot</B> and <B>wclrtobot</B> routines erase from the  cursor
+       The <STRONG>clrtobot</STRONG> and <STRONG>wclrtobot</STRONG> routines erase from the  cursor
        to the end of screen.  That is, they erase all lines below
        the cursor in the window.  Also, the current line  to  the
        right of the cursor, inclusive, is erased.
 
-       The <B>clrtoeol</B> and <B>wclrtoeol</B> routines erase the current line
+       The <STRONG>clrtoeol</STRONG> and <STRONG>wclrtoeol</STRONG> routines erase the current line
        to the right of the cursor, inclusive, to the end  of  the
        current line.
 
        Blanks created by erasure have the current background ren-
-       dition (as set by <B>wbkgdset</B>) merged into them.
+       dition (as set by <STRONG>wbkgdset</STRONG>) merged into them.
 
 
 </PRE>
 <H2>RETURN VALUE</H2><PRE>
-       All routines return the integer  <B>OK</B>.   The  SVr4.0  manual
-       says  "or  a  non-negative integer if <B>immedok</B> is set", but
-       this appears to be an error.
+       All routines return the integer <STRONG>OK</STRONG> on success and  <STRONG>ERR</STRONG>  on
+       failure.   The SVr4.0 manual says "or a non-negative inte-
+       ger if <STRONG>immedok</STRONG> is set", but this appears to be an error.
+
+       X/Open defines no error conditions.  In  this  implementa-
+       tion, functions using a window pointer parameter return an
+       error if it is null.
 
 
 </PRE>
 <H2>NOTES</H2><PRE>
-       Note that <B>erase</B>, <B>werase</B>, <B>clear</B>, <B>wclear</B>, <B>clrtobot</B>, and <B>clr-</B>
-       <B>toeol</B> may be macros.
+       Note that <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clr-</STRONG>
+       <STRONG>toeol</STRONG> may be macros.
 
 
 </PRE>
 <H2>PORTABILITY</H2><PRE>
        These  functions are described in the XSI Curses standard,
-       Issue 4.  The standard specifies that they return  <B>ERR</B>  on
+       Issue 4.  The standard specifies that they return  <STRONG>ERR</STRONG>  on
        failure, but specifies no error conditions.
 
        Some  historic  curses  implementations had, as an undocu-
        mented feature,  the  ability  to  do  the  equivalent  of
-       <B>clearok(...,</B>    <B>1)</B>    by    saying   <B>touchwin(stdscr)</B>   or
-       <B>clear(stdscr)</B>.  This will not work under ncurses.
-
-
-</PRE>
-<H2>SEE ALSO</H2><PRE>
-       <B><A HREF="ncurses.3x.html">curses(3x)</A></B>, <B><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></B>, <B><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></B>
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+       <STRONG>clearok(...,</STRONG>  <STRONG>1)</STRONG>  by saying <STRONG>touchwin(stdscr)</STRONG> or <STRONG>clear(std-</STRONG>
+       <STRONG>scr)</STRONG>.  This will not work under ncurses.
 
+       This implementation, and others such as Solaris, sets  the
+       current  position  to  0,0  after erasing via <STRONG>werase()</STRONG> and
+       <STRONG>wclear()</STRONG>.  That fact is not documented in other  implemen-
+       tations, and may not be true of implementations which were
+       not derived from SVr4 source.
 
+       Not obvious from  the  description,  most  implementations
+       clear  the screen after <STRONG>wclear</STRONG> even for a subwindow or de-
+       rived window.  If you do not want to clear the screen dur-
+       ing the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
 
 
+</PRE>
+<H2>SEE ALSO</H2><PRE>
+       <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_clear.3x.html">curs_clear(3x)</A></STRONG>
 </PRE>
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