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- <div class="titlepage"><div><div><h3 class="title">
- <a name="boost_typetraits.reference.declval"></a><a class="link" href="declval.html" title="declval">declval</a>
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- <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span>
- <span class="keyword">typename</span> <span class="identifier">add_rvalue_reference</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">declval</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span> <span class="comment">// as unevaluated operand</span>
- </pre>
- <p>
- <span class="bold"><strong>C++ Standard Reference:</strong></span> C++11 20.2.4 [declval].
- </p>
- <p>
- <span class="bold"><strong>Header:</strong></span> <code class="computeroutput"> <span class="preprocessor">#include</span>
- <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">declval</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>
- or <code class="computeroutput"> <span class="preprocessor">#include</span> <span class="special"><</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">></span></code>
- </p>
- <p>
- The function template <code class="computeroutput"><span class="identifier">declval</span></code>
- is used when a value of a certain type is required in a type computation
- context. For example, the type of the result of adding an <code class="computeroutput"><span class="keyword">int</span></code>
- and a <code class="computeroutput"><span class="keyword">float</span></code> can be obtained
- with the expression <code class="computeroutput"><span class="keyword">decltype</span><span class="special">(</span> <span class="identifier">declval</span><span class="special"><</span><span class="keyword">int</span><span class="special">>()</span>
- <span class="special">+</span> <span class="identifier">declval</span><span class="special"><</span><span class="keyword">float</span><span class="special">>()</span> <span class="special">)</span></code>.
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- <td align="right"><div class="copyright-footer">Copyright © 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
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