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  27 <a name="core.is_same"></a><a class="link" href="is_same.html" title="is_same">is_same</a>
  28 </h2></div></div></div>
  29 <div class="toc"><dl class="toc"><dt><span class="section"><a href="is_same.html#core.is_same.header_boost_core_is_same_hpp">Header &lt;boost/core/is_same.hpp&gt;</a></span></dt></dl></div>
  30 <div class="simplesect">
  31 <div class="titlepage"><div><div><h3 class="title">
  32 <a name="idp82590272"></a>Authors</h3></div></div></div>
  33 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
  34           Peter Dimov
  35         </li></ul></div>
  36 </div>
  37 <div class="section">
  38 <div class="titlepage"><div><div><h3 class="title">
  39 <a name="core.is_same.header_boost_core_is_same_hpp"></a><a class="link" href="is_same.html#core.is_same.header_boost_core_is_same_hpp" title="Header &lt;boost/core/is_same.hpp&gt;">Header &lt;boost/core/is_same.hpp&gt;</a>
  40 </h3></div></div></div>
  41 <p>
  42         The header <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">core</span><span class="special">/</span><span class="identifier">is_same</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
  43         defines the class template <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">core</span><span class="special">::</span><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">T1</span><span class="special">,</span><span class="identifier">T2</span><span class="special">&gt;</span></code>.
  44         It defines a nested integral constant <code class="computeroutput"><span class="identifier">value</span></code>
  45         which is <code class="computeroutput"><span class="keyword">true</span></code> when <code class="computeroutput"><span class="identifier">T1</span></code> and <code class="computeroutput"><span class="identifier">T2</span></code>
  46         are the same type, and <code class="computeroutput"><span class="keyword">false</span></code>
  47         when they are not.
  48       </p>
  49 <p>
  50         In tandem with <code class="computeroutput"><span class="identifier">BOOST_TEST_TRAIT_TRUE</span></code>
  51         and <code class="computeroutput"><span class="identifier">BOOST_TEST_TRAIT_FALSE</span></code>,
  52         <code class="computeroutput"><span class="identifier">is_same</span></code> is useful for writing
  53         tests for traits classes that have to define specific nested types.
  54       </p>
  55 <div class="section">
  56 <div class="titlepage"><div><div><h4 class="title">
  57 <a name="core.is_same.header_boost_core_is_same_hpp.synopsis"></a><a class="link" href="is_same.html#core.is_same.header_boost_core_is_same_hpp.synopsis" title="Synopsis">Synopsis</a>
  58 </h4></div></div></div>
  59 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
  60 <span class="special">{</span>
  61
  62 <span class="keyword">namespace</span> <span class="identifier">core</span>
  63 <span class="special">{</span>
  64     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">&gt;</span> <span class="keyword">struct</span> <span class="identifier">is_same</span><span class="special">;</span>
  65 <span class="special">}</span>
  66
  67 <span class="special">}</span>
  68 </pre>
  69 </div>
  70 <div class="section">
  71 <div class="titlepage"><div><div><h4 class="title">
  72 <a name="core.is_same.header_boost_core_is_same_hpp.example"></a><a class="link" href="is_same.html#core.is_same.header_boost_core_is_same_hpp.example" title="Example">Example</a>
  73 </h4></div></div></div>
  74 <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">core</span><span class="special">/</span><span class="identifier">lightweight_test_trait</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  75 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">core</span><span class="special">/</span><span class="identifier">is_same</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  76
  77 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">struct</span> <span class="identifier">X</span>
  78 <span class="special">{</span>
  79     <span class="keyword">typedef</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">type</span><span class="special">;</span>
  80 <span class="special">};</span>
  81
  82 <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">core</span><span class="special">::</span><span class="identifier">is_same</span><span class="special">;</span>
  83
  84 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
  85 <span class="special">{</span>
  86     <span class="identifier">BOOST_TEST_TRAIT_TRUE</span><span class="special">((</span> <span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">int</span><span class="special">&amp;&gt;</span> <span class="special">));</span>
  87     <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">report_errors</span><span class="special">();</span>
  88 <span class="special">}</span>
  89 </pre>
  90 </div>
  91 </div>
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  94 <td align="left"></td>
  95 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Peter Dimov<br>Copyright &#169; 2014 Glen Fernandes<br>Copyright &#169; 2014 Andrey Semashev<p>
  96         Distributed under the <a href="http://boost.org/LICENSE_1_0.txt" target="_top">Boost
  97         Software License, Version 1.0</a>.
  98       </p>
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