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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_array.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_binding.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 Bignum</font></td><td><table border="0"><tr><td><font color="white">
Parent:
</font></td><td><font color="white">Integer</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="#Arithmeticoperations"><i>Arithmetic operations</i></a> <a href="#Bitoperations"><i>Bit operations</i></a> <a href="#_lt_eq_lt"><i><=></i></a> <a href="#_ob_cb"><i>[ ]</i></a> <a href="#size"><i>size</i></a> <a href="#to_f"><i>to_f</i></a> <a href="#to_i"><i>to_i</i></a> <a href="#to_s"><i>to_s</i></a> <p></p><hr>
<code>Bignum</code> objects hold integers outside the range of
<code>Fixnum</code>. <code>Bignum</code> objects are created automatically when
integer calculations would otherwise overflow a <code>Fixnum</code>. When a
calculation involving <code>Bignum</code> objects returns a result that will
fit in a <code>Fixnum</code>, the result is automatically converted.
<P></P>
For the purposes of the bitwise operations and <code>[]</code>, a
<code>Bignum</code> is treated as if it were an infinite-length bitstring
with 2's complement representation.
<P></P>
While <code>Fixnum</code> values are immediate, <code>Bignum</code> objects are
not---assignment and parameter passing work with references to
objects, not the objects themselves.
<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="Arithmeticoperations"><b>Arithmetic operations</b></a></font></td><td bgcolor="#ffaaaa">
<P></P>
</td></tr><td></td><td>
<P></P>
Performs various arithmetic operations on <i>big</i>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3">
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">+</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Addition</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">--</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Subtraction</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">*</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Multiplication</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">/</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Division</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">%</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Modulo</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">**</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Exponentiation</td>
</tr>
</table>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="Bitoperations"><b>Bit operations</b></a></font></td><td bgcolor="#ffaaaa">
<P></P>
</td></tr><td></td><td>
<P></P>
Performs various operations on the binary
representations of the <code>Bignum</code>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3">
<tr>
<td colspan="3" valign="top">~ <i>big</i></td>
<td valign="top">Invert bits</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">|</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Bitwise <font size="-2">OR</font></td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">&</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Bitwise <font size="-2">AND</font></td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">^</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Bitwise <font size="-2">EXCLUSIVE</font> <font size="-2">OR</font></td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top"><<</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Left-shift <em>aNumeric</em> bits</td>
</tr>
<tr>
<td valign="top"><i>big</i></td>
<td valign="top">>></td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Right-shift <em>aNumeric</em> bits
(with sign extension)</td>
</tr>
</table>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_lt_eq_lt"><b><=></b></a></font></td><td bgcolor="#ffaaaa">
<i>big</i> <=> <i>aNumeric</i> -> -1, 0, +1
</td></tr><td></td><td>
<P></P>
Comparison---Returns -1, 0, or +1 depending on
whether <i>big</i> is less
than, equal to, or greater than <i>aNumeric</i>. This is the
basis for the tests in <code>Comparable</code>.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_ob_cb"><b>[ ]</b></a></font></td><td bgcolor="#ffaaaa">
<i>big</i>[ <i>n</i> ] -> 0, 1
</td></tr><td></td><td>
<P></P>
Bit Reference---Returns the <em>n</em>th bit in
the (assumed) binary representation of <i>big</i>,
where <i>big</i>[0] is the least significant bit.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="400"><tr><td><pre>
a = 9**15
50.downto(0) do |n|
print a[n]
end
</pre></td></tr></table>
<em>produces:</em>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="400"><tr><td><pre>
000101110110100000111000011110010100111100010111001
</pre></td></tr></table>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="size"><b>size</b></a></font></td><td bgcolor="#ffaaaa">
<i>big</i>.size -> <i>anInteger</i>
</td></tr><td></td><td>
<P></P>
Returns the number of bytes in the machine representation
of <i>big</i>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>(256**10 - 1).size</code></td>
<td valign="top"></td>
<td valign="top"><code>12</code></td>
</tr>
<tr>
<td valign="top"><code>(256**20 - 1).size</code></td>
<td valign="top"></td>
<td valign="top"><code>20</code></td>
</tr>
<tr>
<td valign="top"><code>(256**40 - 1).size</code></td>
<td valign="top"></td>
<td valign="top"><code>40</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_f"><b>to_f</b></a></font></td><td bgcolor="#ffaaaa">
<i>big</i>.to_f -> <i>aFloat</i>
</td></tr><td></td><td>
<P></P>
Converts <i>big</i> to a <code>Float</code>. If <i>big</i> doesn't fit in a
<code>Float</code>, the result is infinity.
<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">
<i>big</i>.to_i -> <i><i>big</i></i>
</td></tr><td></td><td>
<P></P>
Returns <i>big</i>.
<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">
<i>big</i>.to_s -> <i>aString</i>
</td></tr><td></td><td>
<P></P>
Returns a string containing the decimal representation of <i>big</i>.
<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_array.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_binding.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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