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| <div class="section"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="boost_multiprecision.tut.ints.gmp_int"></a><a class="link" href="gmp_int.html" title="gmp_int">gmp_int</a> |
| </h4></div></div></div> |
| <p> |
| <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">gmp</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> |
| </p> |
| <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> |
| |
| <span class="keyword">class</span> <span class="identifier">gmp_int</span><span class="special">;</span> |
| |
| <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_int</span> <span class="special">></span> <span class="identifier">mpz_int</span><span class="special">;</span> |
| |
| <span class="special">}}</span> <span class="comment">// namespaces</span> |
| </pre> |
| <p> |
| The <code class="computeroutput"><span class="identifier">gmp_int</span></code> back-end 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">mpz_int</span></code>. |
| It acts as a thin wrapper around the <a href="http://gmplib.org" target="_top">GMP</a> |
| <code class="computeroutput"><span class="identifier">mpz_t</span></code> to provide an integer |
| type that is a drop-in replacement for the native C++ integer types, but |
| with unlimited precision. |
| </p> |
| <p> |
| As well as the usual conversions from arithmetic and string types, type |
| <code class="computeroutput"><span class="identifier">mpz_int</span></code> is copy constructible |
| and assignable from: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem"> |
| The <a href="http://gmplib.org" target="_top">GMP</a> native types: <code class="computeroutput"><span class="identifier">mpf_t</span></code>, <code class="computeroutput"><span class="identifier">mpz_t</span></code>, |
| <code class="computeroutput"><span class="identifier">mpq_t</span></code>. |
| </li> |
| <li class="listitem"> |
| Instances of <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> that are wrappers around those |
| types: <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_float</span><span class="special"><</span><span class="identifier">N</span><span class="special">></span> <span class="special">></span></code>, <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_rational</span><span class="special">></span></code>. |
| </li> |
| </ul></div> |
| <p> |
| It's also possible to access the underlying <code class="computeroutput"><span class="identifier">mpz_t</span></code> |
| via the <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> |
| member function of <code class="computeroutput"><span class="identifier">gmp_int</span></code>. |
| </p> |
| <p> |
| Things you should know when using this type: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem"> |
| No changes are made to the GMP library's global settings - so you can |
| safely mix this type with existing code that uses <a href="http://gmplib.org" target="_top">GMP</a>. |
| </li> |
| <li class="listitem"> |
| Default constructed <code class="computeroutput"><span class="identifier">gmp_int</span></code>s |
| have the value zero (this is GMP's default behavior). |
| </li> |
| <li class="listitem"> |
| Formatted IO for this type does not support octal or hexadecimal notation |
| for negative values, as a result performing formatted output on this |
| 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> |
| 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> |
| will be thrown. |
| </li> |
| <li class="listitem"> |
| 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> |
| being thrown if the string can not be interpreted as a valid integer. |
| </li> |
| <li class="listitem"> |
| 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> |
| being thrown. |
| </li> |
| <li class="listitem"> |
| Although this type is a wrapper around <a href="http://gmplib.org" target="_top">GMP</a> |
| it will work equally well with <a href="http://mpir.org/" target="_top">MPIR</a>. |
| Indeed use of <a href="http://mpir.org/" target="_top">MPIR</a> is recommended |
| on Win32. |
| </li> |
| <li class="listitem"> |
| This backend supports rvalue-references and is move-aware, making instantiations |
| of <code class="computeroutput"><span class="identifier">number</span></code> on this backend |
| move aware. |
| </li> |
| </ul></div> |
| <h6> |
| <a name="boost_multiprecision.tut.ints.gmp_int.h0"></a> |
| <span class="phrase"><a name="boost_multiprecision.tut.ints.gmp_int.example"></a></span><a class="link" href="gmp_int.html#boost_multiprecision.tut.ints.gmp_int.example">Example:</a> |
| </h6> |
| <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">gmp</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| |
| <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> |
| <span class="special">{</span> |
| <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> |
| |
| <span class="identifier">mpz_int</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> |
| |
| <span class="comment">// Do some arithmetic:</span> |
| <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> |
| <span class="identifier">v</span> <span class="special">*=</span> <span class="identifier">i</span><span class="special">;</span> |
| |
| <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!</span> |
| |
| <span class="comment">// Access the underlying representation:</span> |
| <span class="identifier">mpz_t</span> <span class="identifier">z</span><span class="special">;</span> |
| <span class="identifier">mpz_init</span><span class="special">(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="identifier">mpz_set</span><span class="special">(</span><span class="identifier">z</span><span class="special">,</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">backend</span><span class="special">().</span><span class="identifier">data</span><span class="special">());</span> |
| <span class="identifier">mpz_clear</span><span class="special">(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> |
| <span class="special">}</span> |
| </pre> |
| </div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2002-2013 John Maddock and Christopher Kormanyos<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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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