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<html><title>Programming Ruby: The Pragmatic Programmer's Guide</title><head><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><STYLE TYPE="text/css"><!--
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</STYLE><table bgcolor="#a03030" cellpadding="3" border="0" cellspacing="0"><tr><td colspan="3"><table bgcolor="#902020" cellpadding="20"><tr><td><h1 class="header">Programming Ruby</h1><h3 class="subheader">The Pragmatic Programmer's Guide</h3></td></tr></table></td></tr><tr><td width="33%" align="left"><a class="subheader" href="ref_c_module.html">Previous <</a></td><td width="33%" align="center" valign="middle"><a class="subheader" href="builtins.html">Contents ^</a><br></td><td width="33%" align="right"><a class="subheader" href="ref_c_numeric.html">Next ></a><br></td></tr></table></head><body bgcolor="white">
<!--
Copyright (c) 2001 by Addison Wesley Longman. This
material may be distributed only subject to the terms and
conditions set forth in the Open Publication License, v1.0 or
later (the latest version is presently available at
http://www.opencontent.org/openpub/).
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<table><tr><td height="20"><img src="dot.gif" width="1" height="20"></td></tr></table><table border="0" width="100%" bgcolor="660066" cellpadding="10"><tr><td valign="center"><font color="white" size="7">class NilClass</font></td><td><table border="0"><tr><td><font color="white">
Parent:
</font></td><td><font color="white">Object</font></td></tr><tr><td><font color="white">
Version:
</font></td><td><font color="white">
1.6
</font></td></tr></table></td></tr></table><p></p><H3>Index:</H3><a href="#_et"><i>&</i></a> <a href="#_up"><i>^</i></a> <a href="#_ba"><i>|</i></a> <a href="#nil_qm"><i>nil?</i></a> <a href="#to_a"><i>to_a</i></a> <a href="#to_i"><i>to_i</i></a> <a href="#to_s"><i>to_s</i></a> <p></p><hr>
The class of the singleton object <code>nil</code>.
<P></P>
<table border="0" width="100%" cellpadding="10"><tr><td valign="center" colspan="2" bgcolor="990066"><font color="white" size="6">instance methods
</font></td></tr><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_et"><b>&</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>& <i>anObject</i>
-> <code>false</code>
</td></tr><td></td><td>
<P></P>
And---Returns <code>false</code>. As <i>anObject</i> is an
argument to a method call, it is always evaluated; there is no
short-circuit evaluation in this case.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="400"><tr><td><pre>
nil && puts("logical and")
nil & puts("and")
</pre></td></tr></table>
<em>produces:</em>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="400"><tr><td><pre>
and
</pre></td></tr></table>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_up"><b>^</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>^ <i>anObject</i>
-> <code>true</code> or <code>false</code>
</td></tr><td></td><td>
<P></P>
Exclusive Or---Returns <code>false</code> if <i>anObject</i> is <code>nil</code> or
<code>false</code>,
<code>true</code> otherwise.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_ba"><b>|</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>| <i>anObject</i>
-> <code>true</code> or <code>false</code>
</td></tr><td></td><td>
<P></P>
Or---Returns <code>false</code> if <i>anObject</i> is
<code>nil</code> or <code>false</code>, <code>true</code> otherwise.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="nil_qm"><b>nil?</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>.nil? -> <code>true</code>
</td></tr><td></td><td>
<P></P>
Always returns <code>true</code>.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_a"><b>to_a</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>.to_a -> []
</td></tr><td></td><td>
<P></P>
Always returns an empty array.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_i"><b>to_i</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>.to_i -> 0
</td></tr><td></td><td>
<P></P>
Always returns zero.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_s"><b>to_s</b></a></font></td><td bgcolor="#ffaaaa">
<code>nil</code>.to_s -> ""
</td></tr><td></td><td>
<P></P>
Always returns the empty string.
<P></P>
</td></table>
<P></P>
<p></p><hr><table bgcolor="#a03030" cellpadding="10" border="0" cellspacing="0"><tr><td width="33%" align="left"><a class="subheader" href="ref_c_module.html">Previous <</a></td><td width="33%" align="center" valign="middle"><a class="subheader" href="builtins.html">Contents ^</a><br></td><td width="33%" align="right"><a class="subheader" href="ref_c_numeric.html">Next ></a><br></td></tr></table><p></p><font size="-1">Extracted from the book "Programming Ruby -
The Pragmatic Programmer's Guide"</font><br><font size="-3">
Copyright
©
2000 Addison Wesley Longman, Inc. Released under the terms of the
<a href="http://www.opencontent.org/openpub/">Open Publication License</a> V1.0.
<br>
This reference is available for
<a href="http://www.pragmaticprogrammer.com/ruby/downloads/book.html">download</a>.
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