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  37 <TITLE>curs_clear 3x 2023-09-30 ncurses 6.4 Library calls</TITLE>
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  42 <H1 class="no-header">curs_clear 3x 2023-09-30 ncurses 6.4 Library calls</H1>
  43 <PRE>
  44 <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>
  45
  46
  47
  48
  49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
  50        <STRONG>erase</STRONG>,  <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, <STRONG>wclrtobot</STRONG>, <STRONG>clrtoeol</STRONG>, <STRONG>wclrtoeol</STRONG>
  51        - clear all or part of a <EM>curses</EM> window
  52
  53
  54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
  55        <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
  56
  57        <STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
  58        <STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
  59
  60        <STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
  61        <STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
  62
  63        <STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
  64        <STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
  65
  66        <STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
  67        <STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
  68
  69
  70 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
  71
  72 </PRE><H3><a name="h3-erase_werase">erase/werase</a></H3><PRE>
  73        The <STRONG>erase</STRONG> and <STRONG>werase</STRONG> routines copy blanks  to  every  position  in  the
  74        window, clearing the screen.
  75
  76        Blanks created by erasure have the current background rendition (as set
  77        by <STRONG><A HREF="curs_bkgd.3x.html">wbkgdset(3x)</A></STRONG>) merged into them.
  78
  79
  80 </PRE><H3><a name="h3-clear_wclear">clear/wclear</a></H3><PRE>
  81        The <STRONG>clear</STRONG> and <STRONG>wclear</STRONG> routines are like <STRONG>erase</STRONG> and <STRONG>werase</STRONG>, but they  also
  82        call  <STRONG><A HREF="curs_outopts.3x.html">clearok(3x)</A></STRONG>, so that the screen is cleared completely on the next
  83        call to <STRONG>wrefresh</STRONG> for that window and repainted from scratch.
  84
  85
  86 </PRE><H3><a name="h3-clrtobot_wclrtobot">clrtobot/wclrtobot</a></H3><PRE>
  87        The <STRONG>clrtobot</STRONG> and <STRONG>wclrtobot</STRONG> routines erase from the cursor to the end of
  88        screen.   That is, they erase all lines below the cursor in the window.
  89        Also, the current line to  the  right  of  the  cursor,  inclusive,  is
  90        erased.
  91
  92
  93 </PRE><H3><a name="h3-clrtoeol_wclrtoeol">clrtoeol/wclrtoeol</a></H3><PRE>
  94        The <STRONG>clrtoeol</STRONG> and <STRONG>wclrtoeol</STRONG> routines erase the current line to the right
  95        of the cursor, inclusive, to the end of the current line.
  96
  97
  98 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
  99        All routines return the integer <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
 100
 101        X/Open defines no error conditions.  In this implementation,
 102
 103        <STRONG>o</STRONG>   functions using a window pointer parameter return an error if it is
 104            null
 105
 106        <STRONG>o</STRONG>   <STRONG>wclrtoeol</STRONG> returns an error if the cursor position is about to wrap.
 107
 108
 109 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
 110        Note  that  <STRONG>erase</STRONG>, <STRONG>werase</STRONG>, <STRONG>clear</STRONG>, <STRONG>wclear</STRONG>, <STRONG>clrtobot</STRONG>, and <STRONG>clrtoeol</STRONG> may be
 111        macros.
 112
 113
 114 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
 115        These functions are described in the XSI Curses standard, Issue 4.  The
 116        standard  specifies  that  they return <STRONG>ERR</STRONG> on failure, but specifies no
 117        error conditions.
 118
 119        The SVr4.0 manual says  that  these  functions  could  return  "a  non-
 120        negative  integer if <STRONG><A HREF="curs_outopts.3x.html">immedok(3x)</A></STRONG> is set", referring to the return-value
 121        of <STRONG>wrefresh</STRONG>.  In that implementation, <STRONG>wrefresh</STRONG> would return a count  of
 122        the number of characters written to the terminal.
 123
 124        Some  historic  curses implementations had, as an undocumented feature,
 125        the  ability  to  do  the  equivalent  of  <STRONG>clearok(...,</STRONG>  <STRONG>1)</STRONG>  by  saying
 126        <STRONG>touchwin(stdscr)</STRONG> or <STRONG>clear(stdscr)</STRONG>.  This will not work under ncurses.
 127
 128        This  implementation,  and  others  such  as  Solaris, sets the current
 129        position to 0,0 after erasing via <STRONG>werase</STRONG> and <STRONG>wclear</STRONG>.  That fact is  not
 130        documented   in   other   implementations,  and  may  not  be  true  of
 131        implementations which were not derived from SVr4 source.
 132
 133        Not obvious from the description, most implementations clear the screen
 134        after  <STRONG>wclear</STRONG>  even  for  a subwindow or derived window.  If you do not
 135        want to clear the screen during the next <STRONG>wrefresh</STRONG>, use <STRONG>werase</STRONG> instead.
 136
 137
 138 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
 139        <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>
 140
 141
 142
 143 ncurses 6.4                       2023-09-30                    <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
 144 </PRE>
 145 <div class="nav">
 146 <ul>
 147 <li><a href="#h2-NAME">NAME</a></li>
 148 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
 149 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
 150 <ul>
 151 <li><a href="#h3-erase_werase">erase/werase</a></li>
 152 <li><a href="#h3-clear_wclear">clear/wclear</a></li>
 153 <li><a href="#h3-clrtobot_wclrtobot">clrtobot/wclrtobot</a></li>
 154 <li><a href="#h3-clrtoeol_wclrtoeol">clrtoeol/wclrtoeol</a></li>
 155 </ul>
 156 </li>
 157 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
 158 <li><a href="#h2-NOTES">NOTES</a></li>
 159 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
 160 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
 161 </ul>
 162 </div>
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