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<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_typetraits.reference.decay"></a><a class="link" href="decay.html" title="decay">decay</a>
</h3></div></div></div>
<pre class="programlisting"><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">decay</span>
<span class="special">{</span>
   <span class="keyword">typedef</span> <em class="replaceable"><code>see-below</code></em> <span class="identifier">type</span><span class="special">;</span>
<span class="special">};</span>

<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">using</span> <span class="identifier">decay_t</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span> <span class="comment">// C++11 and above</span>
</pre>
<p>
        <span class="bold"><strong>type:</strong></span> Let <code class="computeroutput"><span class="identifier">U</span></code>
        be the result of <code class="computeroutput"><span class="identifier">remove_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span></code>, then if <code class="computeroutput"><span class="identifier">U</span></code>
        is an array type, the result is <code class="computeroutput"><span class="identifier">remove_extent</span><span class="special">&lt;</span><span class="identifier">U</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">*</span></code>,
        otherwise if <code class="computeroutput"><span class="identifier">U</span></code> is a function
        type then the result is <code class="computeroutput"><span class="identifier">U</span><span class="special">*</span></code>, otherwise the result is <code class="computeroutput"><span class="identifier">remove_cv</span><span class="special">&lt;</span><span class="identifier">U</span><span class="special">&gt;::</span><span class="identifier">type</span></code>.
      </p>
<p>
        <span class="bold"><strong>C++ Standard Reference:</strong></span> 3.9.1.
      </p>
<p>
        <span class="bold"><strong>Header:</strong></span> <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">type_traits</span><span class="special">/</span><span class="identifier">decay</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
        or <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">type_traits</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
      </p>
<div class="table">
<a name="boost_typetraits.reference.decay.examples"></a><p class="title"><b>Table&#160;1.20.&#160;Examples</b></p>
<div class="table-contents"><table class="table" summary="Examples">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  Expression
                </p>
              </th>
<th>
                <p>
                  Result Type
                </p>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">decay</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">[</span><span class="number">2</span><span class="special">][</span><span class="number">3</span><span class="special">]&gt;::</span><span class="identifier">type</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">[</span><span class="number">3</span><span class="special">]*</span></code>
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">decay</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">(&amp;)[</span><span class="number">2</span><span class="special">]&gt;::</span><span class="identifier">type</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">*</span></code>
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">decay</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">(&amp;)(</span><span class="keyword">double</span><span class="special">)&gt;::</span><span class="identifier">type</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">(*)(</span><span class="keyword">double</span><span class="special">)</span></code>
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">(*)(</span><span class="keyword">double</span><span class="special">)</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">(*)(</span><span class="keyword">double</span><span class="special">)</span></code>
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">(</span><span class="keyword">double</span><span class="special">)</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">int</span><span class="special">(*)(</span><span class="keyword">double</span><span class="special">)</span></code>
                </p>
              </td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><p>
        <span class="bold"><strong>Compiler Compatibility:</strong></span> All current compilers
        are supported by this trait.
      </p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2000, 2011 Adobe Systems Inc, David Abrahams,
      Frederic Bron, Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant,
      Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten
      Ottosen, Roman Perepelitsa, Robert Ramey, Jeremy Siek, Robert Stewart and Steven
      Watanabe<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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