ceph/src/boost/libs/multiprecision/doc/html/boost_multiprecision/tut/ints/tom_int.html

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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_multiprecision.tut.ints.tom_int"></a><a class="link" href="tom_int.html" title="tom_int">tom_int</a>
  28 </h4></div></div></div>
  29 <p>
  30           <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">tommath</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
  31         </p>
  32 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">multiprecision</span><span class="special">{</span>
  33
  34 <span class="keyword">class</span> <span class="identifier">tommath_int</span><span class="special">;</span>
  35
  36 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">tommath_int</span> <span class="special">&gt;</span>         <span class="identifier">tom_int</span><span class="special">;</span>
  37
  38 <span class="special">}}</span> <span class="comment">// namespaces</span>
  39 </pre>
  40 <p>
  41           The <code class="computeroutput"><span class="identifier">tommath_int</span></code> back-end
  42           is used via the typedef <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">multiprecision</span><span class="special">::</span><span class="identifier">tom_int</span></code>.
  43           It acts as a thin wrapper around the <a href="http://libtom.org/?page=features&amp;newsitems=5&amp;whatfile=ltm" target="_top">libtommath</a>
  44           <code class="computeroutput"><span class="identifier">tom_int</span></code> to provide an integer
  45           type that is a drop-in replacement for the native C++ integer types, but
  46           with unlimited precision.
  47         </p>
  48 <p>
  49           Things you should know when using this type:
  50         </p>
  51 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  52 <li class="listitem">
  53               Default constructed objects have the value zero (this is <a href="http://libtom.org/?page=features&amp;newsitems=5&amp;whatfile=ltm" target="_top">libtommath</a>'s
  54               default behavior).
  55             </li>
  56 <li class="listitem">
  57               Although <code class="computeroutput"><span class="identifier">tom_int</span></code> is
  58               mostly a drop in replacement for the builtin integer types, it should
  59               be noted that it is a rather strange beast as it's a signed type that
  60               is not a 2's complement type. As a result the bitwise operations <code class="computeroutput"><span class="special">|</span> <span class="special">&amp;</span> <span class="special">^</span></code> will throw a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span></code>
  61               exception if either of the arguments is negative. Similarly the complement
  62               operator<code class="computeroutput"><span class="special">~</span></code> is deliberately
  63               not implemented for this type.
  64             </li>
  65 <li class="listitem">
  66               Formatted IO for this type does not support octal or hexadecimal notation
  67               for negative values, as a result performing formatted output on this
  68               type when the argument is negative and either of the flags <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span><span class="special">::</span><span class="identifier">oct</span></code> or <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span><span class="special">::</span><span class="identifier">hex</span></code>
  69               are set, will result in a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span></code>
  70               will be thrown.
  71             </li>
  72 <li class="listitem">
  73               Conversion from a string results in a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span></code>
  74               being thrown if the string can not be interpreted as a valid integer.
  75             </li>
  76 <li class="listitem">
  77               Division by zero results in a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">overflow_error</span></code>
  78               being thrown.
  79             </li>
  80 </ul></div>
  81 <h6>
  82 <a name="boost_multiprecision.tut.ints.tom_int.h0"></a>
  83           <span class="phrase"><a name="boost_multiprecision.tut.ints.tom_int.example"></a></span><a class="link" href="tom_int.html#boost_multiprecision.tut.ints.tom_int.example">Example:</a>
  84         </h6>
  85 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">tommath</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  86 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
  87
  88 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
  89 <span class="special">{</span>
  90    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">multiprecision</span><span class="special">::</span><span class="identifier">tom_int</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span>
  91
  92    <span class="comment">// Do some arithmetic:</span>
  93    <span class="keyword">for</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;=</span> <span class="number">1000</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
  94       <span class="identifier">v</span> <span class="special">*=</span> <span class="identifier">i</span><span class="special">;</span>
  95
  96    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 1000!</span>
  97    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">hex</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 1000! in hex format</span>
  98
  99    <span class="keyword">try</span><span class="special">{</span>
 100       <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">hex</span> <span class="special">&lt;&lt;</span> <span class="special">-</span><span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// Ooops! can't print a negative value in hex format!</span>
 101    <span class="special">}</span>
 102    <span class="keyword">catch</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span><span class="special">&amp;</span> <span class="identifier">e</span><span class="special">)</span>
 103    <span class="special">{</span>
 104       <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 105    <span class="special">}</span>
 106
 107    <span class="keyword">try</span><span class="special">{</span>
 108       <span class="comment">// v is not a 2's complement type, bitwise operations are only supported</span>
 109       <span class="comment">// on positive values:</span>
 110       <span class="identifier">v</span> <span class="special">=</span> <span class="special">-</span><span class="identifier">v</span> <span class="special">&amp;</span> <span class="number">2</span><span class="special">;</span>
 111    <span class="special">}</span>
 112    <span class="keyword">catch</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span><span class="special">&amp;</span> <span class="identifier">e</span><span class="special">)</span>
 113    <span class="special">{</span>
 114       <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">()</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 115    <span class="special">}</span>
 116
 117    <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 118 <span class="special">}</span>
 119 </pre>
 120 </div>
 121 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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 123 <td align="right"><div class="copyright-footer">Copyright &#169; 2002-2013 John Maddock and Christopher Kormanyos<p>
 124         Distributed under the Boost Software License, Version 1.0. (See accompanying
 125         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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