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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_typetraits.reference.is_pointer"></a><a class="link" href="is_pointer.html" title="is_pointer"> is_pointer</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="keyword">struct</span> <span class="identifier">is_pointer</span> <span class="special">:</span> <span class="keyword">public</span> <em class="replaceable"><code><a class="link" href="integral_constant.html" title="integral_constant">true_type</a>-or-<a class="link" href="integral_constant.html" title="integral_constant">false_type</a></code></em> <span class="special">{};</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Inherits:</strong></span> If T is a (possibly cv-qualified) |
| pointer type (includes function pointers, but excludes pointers to members) |
| then inherits from <a class="link" href="integral_constant.html" title="integral_constant">true_type</a>, |
| otherwise inherits from <a class="link" href="integral_constant.html" title="integral_constant">false_type</a>. |
| </p> |
| <p> |
| <span class="bold"><strong>C++ Standard Reference:</strong></span> 3.9.2p2 and 8.3.1. |
| </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">is_pointer</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">is_pointer</span><span class="special"><</span><span class="keyword">int</span><span class="special">*></span></code> |
| inherits from <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">true_type</a></code>. |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</span><span class="special"><</span><span class="keyword">char</span><span class="special">*</span> <span class="keyword">const</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">true_type</a></code>. |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</span><span class="special"><</span><span class="keyword">int</span> <span class="special">(*)(</span><span class="keyword">long</span><span class="special">)>::</span><span class="identifier">value</span></code> is an integral constant expression |
| that evaluates to <span class="emphasis"><em>true</em></span>. |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</span><span class="special"><</span><span class="keyword">int</span> <span class="special">(</span><span class="identifier">MyClass</span><span class="special">::*)(</span><span class="keyword">long</span><span class="special">)>::</span><span class="identifier">value</span></code> |
| is an integral constant expression that evaluates to <span class="emphasis"><em>false</em></span>. |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</span><span class="special"><</span><span class="keyword">int</span> <span class="special">(</span><span class="identifier">MyClass</span><span class="special">::*)>::</span><span class="identifier">value</span></code> |
| is an integral constant expression that evaluates to <span class="emphasis"><em>false</em></span>. |
| </p></blockquote></div> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</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="keyword">bool</span></code>. |
| </p></blockquote></div> |
| <div class="important"><table border="0" summary="Important"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../../doc/src/images/important.png"></td> |
| <th align="left">Important</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| <code class="computeroutput"><span class="identifier">is_pointer</span></code> detects "real" |
| pointer types only, and <span class="emphasis"><em>not</em></span> smart pointers. Users |
| should not specialise <code class="computeroutput"><span class="identifier">is_pointer</span></code> |
| for smart pointer types, as doing so may cause Boost (and other third party) |
| code to fail to function correctly. Users wanting a trait to detect smart |
| pointers should create their own. However, note that there is no way in |
| general to auto-magically detect smart pointer types, so such a trait would |
| have to be partially specialised for each supported smart pointer type. |
| </p></td></tr> |
| </table></div> |
| </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 © 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>) |
| </p> |
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