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<H1 class="no-header">curs_clear 3x 2025-01-18 ncurses 6.6 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<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 <EM>curses</EM> window
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
<STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
<STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
<STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
<STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
</PRE><H3><a name="h3-erase_werase">erase, werase</a></H3><PRE>
The <STRONG>erase</STRONG> and <STRONG>werase</STRONG> routines copy blanks to every position in the
window, clearing the screen.
Blanks created by erasure have the current background rendition (as set
by <STRONG><A HREF="curs_bkgd.3x.html">wbkgdset(3x)</A></STRONG>) merged into them.
</PRE><H3><a name="h3-clear_wclear">clear, wclear</a></H3><PRE>
The <STRONG>clear</STRONG> and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>, but they also
call <STRONG><A HREF="curs_outopts.3x.html">clearok(3x)</A></STRONG>, so that the screen is cleared completely on the next
call to <STRONG>wrefresh</STRONG> for that window and repainted from scratch.
</PRE><H3><a name="h3-clrtobot_wclrtobot">clrtobot, wclrtobot</a></H3><PRE>
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.
</PRE><H3><a name="h3-clrtoeol_wclrtoeol">clrtoeol, wclrtoeol</a></H3><PRE>
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.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
All routines return the integer <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
In this implementation,
<STRONG>o</STRONG> functions using a window pointer parameter return <STRONG>ERR</STRONG> if it is null
<STRONG>o</STRONG> <STRONG>wclrtoeol</STRONG> returns an error if the cursor position is about to wrap.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
<STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clrtoeol</STRONG> may be implemented
as macros.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
X/Open Curses Issue 4 describes these functions. It specifies no error
conditions for them.
SVr4 documentation says that these functions return <EM>OK</EM> "or a non-
negative integer if <EM>immedok()</EM> is set", referring to the return value
from <EM>wrefresh</EM>, which in SVr4 returns a count of characters written to
the window if its <EM>immedok</EM> property is set; in <EM>ncurses</EM>, it does not.
Some historic curses implementations had, as an undocumented feature,
the ability to do the equivalent of <STRONG>clearok(...,</STRONG> <STRONG>1)</STRONG> by saying
<STRONG>touchwin(stdscr)</STRONG> or <STRONG>clear(stdscr)</STRONG>. This will not work under <EM>ncurses</EM>.
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 implementations, 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 derived window. If you do not
want to clear the screen during the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></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_variables.3x.html">curs_variables(3x)</A></STRONG>
ncurses 6.6 2025-01-18 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-erase_werase">erase, werase</a></li>
<li><a href="#h3-clear_wclear">clear, wclear</a></li>
<li><a href="#h3-clrtobot_wclrtobot">clrtobot, wclrtobot</a></li>
<li><a href="#h3-clrtoeol_wclrtoeol">clrtoeol, wclrtoeol</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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