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30 * @Id: curs_clear.3x,v 1.27 2022/11/26 16:23:47 tom Exp @
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37 <TITLE>curs_clear 3x</TITLE>
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42 <H1 class="no-header">curs_clear 3x</H1>
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>
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 <STRONG>curses</STRONG> window
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
57 <STRONG>int</STRONG> <STRONG>erase(void);</STRONG>
58 <STRONG>int</STRONG> <STRONG>werase(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
60 <STRONG>int</STRONG> <STRONG>clear(void);</STRONG>
61 <STRONG>int</STRONG> <STRONG>wclear(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
63 <STRONG>int</STRONG> <STRONG>clrtobot(void);</STRONG>
64 <STRONG>int</STRONG> <STRONG>wclrtobot(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
66 <STRONG>int</STRONG> <STRONG>clrtoeol(void);</STRONG>
67 <STRONG>int</STRONG> <STRONG>wclrtoeol(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
70 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
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 win-
74 dow, clearing the screen.
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.
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.
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
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.
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.
101 X/Open defines no error conditions. In this implementation,
103 <STRONG>o</STRONG> functions using a window pointer parameter return an error if it is
106 <STRONG>o</STRONG> <STRONG>wclrtoeol</STRONG> returns an error if the cursor position is about to wrap.
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
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
119 The SVr4.0 manual says that these functions could return "a non-nega-
120 tive integer if <STRONG><A HREF="curs_outopts.3x.html">immedok(3x)</A></STRONG> is set", referring to the return-value of
121 <STRONG>wrefresh</STRONG>. In that implementation, <STRONG>wrefresh</STRONG> would return a count of the
122 number of characters written to the terminal.
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 <STRONG>touch-</STRONG>
126 <STRONG>win(stdscr)</STRONG> or <STRONG>clear(stdscr)</STRONG>. This will not work under ncurses.
128 This implementation, and others such as Solaris, sets the current posi-
129 tion to 0,0 after erasing via <STRONG>werase</STRONG> and <STRONG>wclear</STRONG>. That fact is not doc-
130 umented in other implementations, and may not be true of implementa-
131 tions which were not derived from SVr4 source.
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.
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>
143 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>
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>
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>
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>