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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="align.examples"></a><a class="link" href="examples.html" title="Examples">Examples</a>
</h2></div></div></div>
<h4>
<a name="align.examples.h0"></a>
<span class="phrase"><a name="align.examples.aligned_allocation"></a></span><a class="link" href="examples.html#align.examples.aligned_allocation">Aligned
allocation</a>
</h4>
<p>
To dynamically allocate storage with desired alignment, you can use the <code class="computeroutput"><span class="identifier">aligned_alloc</span></code> function:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="keyword">void</span><span class="special">*</span>
<span class="identifier">storage</span> <span class="special">=</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_alloc</span><span class="special">(</span><span class="identifier">alignment</span><span class="special">,</span>
<span class="identifier">size</span><span class="special">);</span></code>
</li></ol></div>
<p>
To deallocate storage allocated with the <code class="computeroutput"><span class="identifier">aligned_alloc</span></code>
function, use the <code class="computeroutput"><span class="identifier">aligned_free</span></code>
function:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_free</span><span class="special">(</span><span class="identifier">storage</span><span class="special">);</span></code>
</li></ol></div>
<h4>
<a name="align.examples.h1"></a>
<span class="phrase"><a name="align.examples.aligned_allocator"></a></span><a class="link" href="examples.html#align.examples.aligned_allocator">Aligned
allocator</a>
</h4>
<p>
For C++ allocator aware code, you can use the <code class="computeroutput"><span class="identifier">aligned_allocator</span></code>
class template for an allocator that respects over-alignment:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">int128_t</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_allocator</span><span class="special"><</span><span class="identifier">int128_t</span><span class="special">></span>
<span class="special">></span> <span class="identifier">vector</span><span class="special">;</span></code>
</li></ol></div>
<p>
This template allows specifying minimum alignment for all dynamic allocations:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_allocator</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="number">64</span><span class="special">></span> <span class="special">></span>
<span class="identifier">vector</span><span class="special">;</span></code>
</li></ol></div>
<h4>
<a name="align.examples.h2"></a>
<span class="phrase"><a name="align.examples.aligned_allocator_adaptor"></a></span><a class="link" href="examples.html#align.examples.aligned_allocator_adaptor">Aligned
allocator adaptor</a>
</h4>
<p>
To turn an allocator into an allocator that respects over-alignment, you can
use the <code class="computeroutput"><span class="identifier">aligned_allocator_adaptor</span></code>
class template:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_allocator_adaptor</span><span class="special"><</span><span class="identifier">First</span><span class="special">></span> <span class="identifier">second</span><span class="special">(</span><span class="identifier">first</span><span class="special">);</span></code>
</li></ol></div>
<p>
This template allows specifying minimum alignment for all dynamic allocations:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_allocator_adaptor</span><span class="special"><</span><span class="identifier">First</span><span class="special">,</span> <span class="number">64</span><span class="special">></span> <span class="identifier">second</span><span class="special">(</span><span class="identifier">first</span><span class="special">);</span></code>
</li></ol></div>
<h4>
<a name="align.examples.h3"></a>
<span class="phrase"><a name="align.examples.aligned_deleter"></a></span><a class="link" href="examples.html#align.examples.aligned_deleter">Aligned
deleter</a>
</h4>
<p>
For a deleter that can be paired with <code class="computeroutput"><span class="identifier">aligned_alloc</span></code>,
you can use the <code class="computeroutput"><span class="identifier">aligned_delete</span></code>
class:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">unique_ptr</span><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">aligned_delete</span><span class="special">></span>
<span class="identifier">pointer</span><span class="special">;</span></code>
</li></ol></div>
<h4>
<a name="align.examples.h4"></a>
<span class="phrase"><a name="align.examples.pointer_alignment"></a></span><a class="link" href="examples.html#align.examples.pointer_alignment">Pointer
alignment</a>
</h4>
<p>
To advance a pointer to the next address with the desired alignment:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<code class="computeroutput"><span class="keyword">void</span><span class="special">*</span>
<span class="identifier">pointer</span> <span class="special">=</span>
<span class="identifier">storage</span><span class="special">;</span></code>
</li>
<li class="listitem">
<code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">space</span>
<span class="special">=</span> <span class="identifier">size</span><span class="special">;</span></code>
</li>
<li class="listitem">
<code class="computeroutput"><span class="keyword">void</span><span class="special">*</span>
<span class="identifier">result</span> <span class="special">=</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">align</span><span class="special">(</span><span class="number">64</span><span class="special">,</span> <span class="keyword">sizeof</span><span class="special">(</span><span class="keyword">double</span><span class="special">),</span> <span class="identifier">pointer</span><span class="special">,</span> <span class="identifier">space</span><span class="special">);</span></code>
</li>
</ol></div>
<h4>
<a name="align.examples.h5"></a>
<span class="phrase"><a name="align.examples.querying_alignment"></a></span><a class="link" href="examples.html#align.examples.querying_alignment">Querying
alignment</a>
</h4>
<p>
To obtain the alignment of a given type at compie time, you can use:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">alignment_of</span><span class="special"><</span><span class="identifier">int128_t</span><span class="special">>::</span><span class="identifier">value</span></code>
</li></ol></div>
<p>
If your compiler supports C++14 variable templates, you can also use:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">alignment_of_v</span><span class="special"><</span><span class="identifier">int128_t</span><span class="special">></span></code>
</li></ol></div>
<h4>
<a name="align.examples.h6"></a>
<span class="phrase"><a name="align.examples.hinting_alignment"></a></span><a class="link" href="examples.html#align.examples.hinting_alignment">Hinting
alignment</a>
</h4>
<p>
To inform the compiler about the alignment of a pointer, you can use:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">BOOST_ALIGN_ASSUME_ALIGNED</span><span class="special">(</span><span class="identifier">pointer</span><span class="special">,</span> <span class="number">64</span><span class="special">)</span></code>
</li></ol></div>
<h4>
<a name="align.examples.h7"></a>
<span class="phrase"><a name="align.examples.checking_alignment"></a></span><a class="link" href="examples.html#align.examples.checking_alignment">Checking
alignment</a>
</h4>
<p>
To check alignment of a pointer you can use the <code class="computeroutput"><span class="identifier">is_aligned</span></code>
function:
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<code class="computeroutput"><span class="identifier">assert</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">alignment</span><span class="special">::</span><span class="identifier">is_aligned</span><span class="special">(</span><span class="identifier">pointer</span><span class="special">,</span> <span class="number">64</span><span class="special">));</span></code>
</li></ol></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2014-2017 Glen
Joseph Fernandes<p>
Distributed under the Boost Software License, Version 1.0.
</p>
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