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25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h4 class="title"> | |
27 | <a name="boost_multiprecision.tut.rational.cpp_rational"></a><a class="link" href="cpp_rational.html" title="cpp_rational">cpp_rational</a> | |
28 | </h4></div></div></div> | |
29 | <p> | |
30 | <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">cpp_int</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></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">typedef</span> <span class="identifier">rational_adaptor</span><span class="special"><</span><span class="identifier">cpp_int_backend</span><span class="special"><></span> <span class="special">></span> <span class="identifier">cpp_rational_backend</span><span class="special">;</span> | |
35 | ||
36 | <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special"><</span><span class="identifier">cpp_rational_backend</span><span class="special">></span> <span class="identifier">cpp_rational</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">cpp_rational_backend</span></code> | |
42 | type 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">cpp_rational</span></code>. | |
43 | It provides a rational number type that is a drop-in replacement for the | |
44 | native C++ number types, but with unlimited precision. | |
45 | </p> | |
46 | <p> | |
47 | As well as the usual conversions from arithmetic and string types, instances | |
48 | of <code class="computeroutput"><span class="identifier">cpp_rational</span></code> are copy | |
49 | constructible and assignable from type <code class="computeroutput"><span class="identifier">cpp_int</span></code>. | |
50 | </p> | |
51 | <p> | |
52 | There is also a two argument constructor that accepts a numerator and denominator: | |
53 | both of type <code class="computeroutput"><span class="identifier">cpp_int</span></code>. | |
54 | </p> | |
55 | <p> | |
56 | There are also non-member functions: | |
57 | </p> | |
58 | <pre class="programlisting"><span class="identifier">cpp_int</span> <span class="identifier">numerator</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">cpp_rational</span><span class="special">&);</span> | |
59 | <span class="identifier">cpp_int</span> <span class="identifier">denominator</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">cpp_rational</span><span class="special">&);</span> | |
60 | </pre> | |
61 | <p> | |
62 | which return the numerator and denominator of the number. | |
63 | </p> | |
64 | <p> | |
65 | Things you should know when using this type: | |
66 | </p> | |
67 | <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> | |
68 | <li class="listitem"> | |
69 | Default constructed <code class="computeroutput"><span class="identifier">cpp_rational</span></code>s | |
70 | have the value zero. | |
71 | </li> | |
72 | <li class="listitem"> | |
73 | 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> | |
74 | being thrown. | |
75 | </li> | |
76 | <li class="listitem"> | |
77 | 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> | |
78 | being thrown if the string can not be interpreted as a valid rational | |
79 | number. | |
80 | </li> | |
81 | </ul></div> | |
82 | <h6> | |
83 | <a name="boost_multiprecision.tut.rational.cpp_rational.h0"></a> | |
84 | <span class="phrase"><a name="boost_multiprecision.tut.rational.cpp_rational.example"></a></span><a class="link" href="cpp_rational.html#boost_multiprecision.tut.rational.cpp_rational.example">Example:</a> | |
85 | </h6> | |
86 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">cpp_int</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> | |
87 | <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> | |
88 | ||
89 | <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> | |
90 | <span class="special">{</span> | |
91 | <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">multiprecision</span><span class="special">;</span> | |
92 | ||
93 | <span class="identifier">cpp_rational</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> | |
94 | ||
95 | <span class="comment">// Do some arithmetic:</span> | |
96 | <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"><=</span> <span class="number">1000</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> | |
97 | <span class="identifier">v</span> <span class="special">*=</span> <span class="identifier">i</span><span class="special">;</span> | |
98 | <span class="identifier">v</span> <span class="special">/=</span> <span class="number">10</span><span class="special">;</span> | |
99 | ||
100 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">v</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 1000! / 10</span> | |
101 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">numerator</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
102 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">denominator</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
103 | ||
104 | <span class="identifier">cpp_rational</span> <span class="identifier">w</span><span class="special">(</span><span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">);</span> <span class="comment">// component wise constructor</span> | |
105 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">w</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 2/3</span> | |
106 | <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> | |
107 | <span class="special">}</span> | |
108 | </pre> | |
109 | </div> | |
110 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
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112 | <td align="right"><div class="copyright-footer">Copyright © 2002-2013 John Maddock and Christopher Kormanyos<p> | |
113 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
114 | 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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