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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_typetraits.reference.extent"></a><a class="link" href="extent.html" title="extent"> extent</a>
</h3></div></div></div>
<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="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span> <span class="special">=</span> <span class="number">0</span><span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">extent</span> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">EXTENT</span><span class="special">(</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">N</span><span class="special">)></span> <span class="special">{};</span>
</pre>
<p>
<span class="bold"><strong>Inherits:</strong></span> Class template extent inherits
from <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="identifier">EXTENT</span><span class="special">(</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">N</span><span class="special">)></span></code>,
where <code class="computeroutput"><span class="identifier">EXTENT</span><span class="special">(</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">N</span><span class="special">)</span></code> is the number of elements in the N'th array
dimension of type <code class="computeroutput"><span class="identifier">T</span></code>.
</p>
<p>
If <code class="computeroutput"><span class="identifier">T</span></code> is not a (built-in)
array type, or if <code class="computeroutput"><span class="identifier">N</span> <span class="special">></span>
<a class="link" href="rank.html" title="rank">rank</a><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span></code>, or if the N'th array bound is incomplete,
then <code class="computeroutput"><span class="identifier">EXTENT</span><span class="special">(</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">N</span><span class="special">)</span></code> is zero.
</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">extent</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>
<span class="bold"><strong>Examples:</strong></span>
</p>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">int</span><span class="special">[</span><span class="number">1</span><span class="special">]></span></code> inherits from <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">1</span><span class="special">></span></code>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">double</span><span class="special">[</span><span class="number">2</span><span class="special">][</span><span class="number">3</span><span class="special">][</span><span class="number">4</span><span class="special">],</span>
<span class="number">0</span><span class="special">>::</span><span class="identifier">type</span></code> is the type <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">2</span><span class="special">></span></code>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">double</span><span class="special">[</span><span class="number">2</span><span class="special">][</span><span class="number">3</span><span class="special">][</span><span class="number">4</span><span class="special">],</span>
<span class="number">1</span><span class="special">>::</span><span class="identifier">type</span></code> is the type <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">3</span><span class="special">></span></code>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">double</span><span class="special">[</span><span class="number">2</span><span class="special">][</span><span class="number">3</span><span class="special">][</span><span class="number">4</span><span class="special">],</span>
<span class="number">3</span><span class="special">>::</span><span class="identifier">type</span></code> is the type <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">integral_constant</a><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> <span class="number">4</span><span class="special">></span></code>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">int</span><span class="special">[</span><span class="number">4</span><span class="special">]>::</span><span class="identifier">value</span></code>
is an integral constant expression that evaluates to <span class="emphasis"><em>4</em></span>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">int</span><span class="special">[][</span><span class="number">2</span><span class="special">]>::</span><span class="identifier">value</span></code>
is an integral constant expression that evaluates to <span class="emphasis"><em>0</em></span>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">int</span><span class="special">[][</span><span class="number">2</span><span class="special">],</span> <span class="number">1</span><span class="special">>::</span><span class="identifier">value</span></code> is an integral constant expression
that evaluates to <span class="emphasis"><em>2</em></span>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="keyword">int</span><span class="special">*>::</span><span class="identifier">value</span></code> is an integral constant expression
that evaluates to <span class="emphasis"><em>0</em></span>.
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="number">3</span><span class="special">></span> <span class="special">>::</span><span class="identifier">value</span></code> is an integral constant expression
that evaluates to <span class="emphasis"><em>0</em></span>: <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span></code>
is a class type and <span class="bold"><strong>not an array type</strong></span>!
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="identifier">extent</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value_type</span></code> is the type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span></code>.
</p></blockquote></div>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2000, 2006 Adobe Systems Inc, David Abrahams,
Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant, Jesse Jones, Mat
Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten Ottosen, Robert
Ramey and Jeremy Siek<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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