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| <div><h2 class="title"> |
| <a name="array"></a>Chapter 3. Boost.Array</h2></div> |
| <div><div class="author"><h3 class="author"> |
| <span class="firstname">Nicolai</span> <span class="surname">Josuttis</span> |
| </h3></div></div> |
| <div><p class="copyright">Copyright © 2001-2004 Nicolai M. Josuttis</p></div> |
| <div><div class="legalnotice"> |
| <a name="id1012944"></a><p>Distributed under the Boost Software License, Version 1.0. |
| (See accompanying file <code class="filename">LICENSE_1_0.txt</code> 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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| <p><b>Table of Contents</b></p> |
| <dl> |
| <dt><span class="section"><a href="array.html#array.intro">Introduction</a></span></dt> |
| <dt><span class="section"><a href="array/reference.html">Reference</a></span></dt> |
| <dd><dl><dt><span class="section"><a href="array/reference.html#header.boost.array_hpp">Header <boost/array.hpp></a></span></dt></dl></dd> |
| <dt><span class="section"><a href="array/rationale.html">Design Rationale</a></span></dt> |
| <dt><span class="section"><a href="array/more/info.html">For more information...</a></span></dt> |
| <dt><span class="section"><a href="array/ack.html">Acknowledgements</a></span></dt> |
| </dl> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="array.intro"></a>Introduction</h2></div></div></div> |
| <p>The C++ Standard Template Library STL as part of the C++ |
| Standard Library provides a framework for processing algorithms on |
| different kind of containers. However, ordinary arrays don't |
| provide the interface of STL containers (although, they provide |
| the iterator interface of STL containers).</p> |
| <p>As replacement for ordinary arrays, the STL provides class |
| <code class="computeroutput">std::vector</code>. However, |
| <code class="computeroutput">std::vector<></code> provides |
| the semantics of dynamic arrays. Thus, it manages data to be able |
| to change the number of elements. This results in some overhead in |
| case only arrays with static size are needed.</p> |
| <p>In his book, <span class="emphasis"><em>Generic Programming and the |
| STL</em></span>, Matthew H. Austern introduces a useful wrapper |
| class for ordinary arrays with static size, called |
| <code class="computeroutput">block</code>. It is safer and has no worse performance than |
| ordinary arrays. In <span class="emphasis"><em>The C++ Programming |
| Language</em></span>, 3rd edition, Bjarne Stroustrup introduces a |
| similar class, called <code class="computeroutput">c_array</code>, which I (<a href="http://www.josuttis.com" target="_top">Nicolai Josuttis</a>) present |
| slightly modified in my book <span class="emphasis"><em>The C++ Standard Library - |
| A Tutorial and Reference</em></span>, called |
| <code class="computeroutput">carray</code>. This is the essence of these approaches |
| spiced with many feedback from <a href="http://www.boost.org" target="_top">boost</a>.</p> |
| <p>After considering different names, we decided to name this |
| class simply <code class="computeroutput"><a class="link" href="boost/array.html" title="Class template array">array</a></code>.</p> |
| <p>Note that this class is suggested to be part of the next |
| Technical Report, which will extend the C++ Standard (see |
| <a href="http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1548.htm" target="_top">http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1548.htm</a>).</p> |
| <p>Class <code class="computeroutput"><a class="link" href="boost/array.html" title="Class template array">array</a></code> fulfills most |
| but not all of the requirements of "reversible containers" (see |
| Section 23.1, [lib.container.requirements] of the C++ |
| Standard). The reasons array is not an reversible STL container is |
| because: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc" compact> |
| <li class="listitem">No constructors are provided.</li> |
| <li class="listitem">Elements may have an undetermined initial value (see <a class="xref" href="array/rationale.html" title="Design Rationale">the section called “Design Rationale”</a>).</li> |
| <li class="listitem"> |
| <code class="computeroutput"><a class="link" href="boost/array.html#boost.array.swap_id426267">swap</a></code>() has no constant complexity.</li> |
| <li class="listitem"> |
| <code class="computeroutput"><a class="link" href="boost/array.html#id425918-bb">size</a></code>() is always constant, based on the second template argument of the type.</li> |
| <li class="listitem">The container provides no allocator support.</li> |
| </ul></div> |
| <p> |
| </p> |
| <p>It doesn't fulfill the requirements of a "sequence" (see Section 23.1.1, [lib.sequence.reqmts] of the C++ Standard), except that: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc" compact> |
| <li class="listitem"> |
| <code class="computeroutput"><a class="link" href="boost/array.html#id426077-bb">front</a></code>() and <code class="computeroutput"><a class="link" href="boost/array.html#id426110-bb">back</a></code>() are provided.</li> |
| <li class="listitem"> |
| <code class="computeroutput"><a class="link" href="boost/array.html#id425972-bb">operator[]</a></code> and <code class="computeroutput"><a class="link" href="boost/array.html#id426024-bb">at</a></code>() are provided.</li> |
| </ul></div> |
| <p> |
| </p> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"><p><small>Last revised: November 01, 2010 at 13:12:40 +0000</small></p></td> |
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