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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="fusion.sequence.intrinsic.metafunctions.value_at"></a><a class="link" href="value_at.html" title="value_at">value_at</a> |
| </h5></div></div></div> |
| <a name="fusion.sequence.intrinsic.metafunctions.value_at.description"></a><h6> |
| <a name="id895720"></a> |
| <a class="link" href="value_at.html#fusion.sequence.intrinsic.metafunctions.value_at.description">Description</a> |
| </h6> |
| <p> |
| Returns the actual type at a given index from the <a class="link" href="../../../sequence.html" title="Sequence">Sequence</a>. |
| </p> |
| <a name="fusion.sequence.intrinsic.metafunctions.value_at.synopsis"></a><h6> |
| <a name="id895748"></a> |
| <a class="link" href="value_at.html#fusion.sequence.intrinsic.metafunctions.value_at.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">Seq</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">N</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">value_at</span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <div class="table"> |
| <a name="id895834"></a><p class="title"><b>Table 1.31. Parameters</b></p> |
| <div class="table-contents"><table class="table" summary="Parameters"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Requirement |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">Seq</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A model of <a class="link" href="../../concepts/forward_sequence.html" title="Forward Sequence">Forward |
| Sequence</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Argument sequence |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">N</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL |
| Integral Constant</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Index of element |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"><a name="fusion.sequence.intrinsic.metafunctions.value_at.expression_semantics"></a><h6> |
| <a name="id895960"></a> |
| <a class="link" href="value_at.html#fusion.sequence.intrinsic.metafunctions.value_at.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <pre class="programlisting"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at</span><span class="special"><</span><span class="identifier">Seq</span><span class="special">,</span> <span class="identifier">N</span><span class="special">>::</span><span class="identifier">type</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Return type</strong></span>: Any type. |
| </p> |
| <p> |
| <span class="bold"><strong>Semantics</strong></span>: Returns the actual type at |
| the <code class="computeroutput"><span class="identifier">N</span></code>th element of <code class="computeroutput"><span class="identifier">Seq</span></code>. |
| </p> |
| <a name="fusion.sequence.intrinsic.metafunctions.value_at.header"></a><h6> |
| <a name="id896043"></a> |
| <a class="link" href="value_at.html#fusion.sequence.intrinsic.metafunctions.value_at.header">Header</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">fusion</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">/</span><span class="identifier">intrinsic</span><span class="special">/</span><span class="identifier">value_at</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">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">value_at</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <a name="fusion.sequence.intrinsic.metafunctions.value_at.example"></a><h6> |
| <a name="id896160"></a> |
| <a class="link" href="value_at.html#fusion.sequence.intrinsic.metafunctions.value_at.example">Example</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">typedef</span> <a class="link" href="../../../container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">float</span><span class="special">,</span><span class="keyword">char</span><span class="special">></span> <span class="identifier">vec</span><span class="special">;</span> |
| <span class="identifier">BOOST_MPL_ASSERT</span><span class="special">((</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special"><</span><a class="link" href="value_at.html" title="value_at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at</span></code></a><span class="special"><</span><span class="identifier">vec</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">int_</span><span class="special"><</span><span class="number">1</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">float</span><span class="special">>));</span> |
| </pre> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias |
| Schwinger<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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