ceph/src/boost/libs/preprocessor/doc/data/arrays.html

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   8     <h4>Arrays</h4>
   9     <div> An <i>array</i> is a data structure consisting of a two-element <i>tuple</i>.&nbsp;
  10       The first element is the number of elements in the <i>array</i>.&nbsp;
  11       The second element is another <i>tuple</i> of the elements in the <i>array</i>.&nbsp;
  12       For example, </div>
  13     <div class="code"> (<i>3</i>, (<i>a</i>, <i>b</i>, <i>c</i>)) </div>
  14     <div> ...is an <i>array</i> of <i>3</i> elements--<i>a</i>, <i>b</i>, and
  15       <i>c</i>. </div>
  16     <div> The primary strength of <i>arrays</i> is that they store their own
  17       size.&nbsp; Because of this, access to elements does not require the
  18       size.&nbsp; It only requires that an element exists at a certain index. </div>
  19     <div> This allows macro parameters to be variable in size and allows data
  20       states to change size without the user explicitly keeping track of the
  21       size independently.<br>
  22       <br>
  23       An <i>array </i>can be empty and have no elements. An empty array has a
  24       0 size. The notation for an empty array is '(0,())'.<br>
  25       <br>
  26       <span style="font-style: italic;"> </span></div>
  27     <div>With variadic macro support a <i>tuple </i>has all of the
  28       functionality as an <i>array</i>, knows its own size, and is easier
  29       syntactically to use. Because of that an <i>array</i> should be used, as
  30       opposed to a <i>tuple</i>, only if your compiler does not support
  31       variadic macros. The only advantage an <i>array </i>has over a <i>tuple
  32       </i>is that an <i>array </i>can be empty while a <i>tuple </i>always
  33       has at least one element and therefore can never have a size of 0.<br>
  34       <br>
  35       Elements of an <i>array</i> can be extracted with <b>BOOST_PP_ARRAY_ELEM</b>,
  36       an <i>array's</i> size can be extracted with <b>BOOST_PP_ARRAY_SIZE</b>,
  37       and an <i>array</i> can be converted to the more primitive <i>tuple</i>
  38       data structure with <b>BOOST_PP_ARRAY_DATA</b>. </div>
  39     <h4>Primitives</h4>
  40     <ul>
  41       <li><a href="../ref/array_data.html">BOOST_PP_ARRAY_DATA</a></li>
  42       <li><a href="../ref/array_elem.html">BOOST_PP_ARRAY_ELEM</a></li>
  43       <li><a href="../ref/array_size.html">BOOST_PP_ARRAY_SIZE</a></li>
  44     </ul>
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  46     <div style="margin-left: 0px;"> <i>© Copyright <a href="http://www.housemarque.com"
  47           target="_top">Housemarque Oy</a> 2002</i> <br>
  48       <i>© Copyright Paul Mensonides 2002</i> </div>
  49     <div style="margin-left: 0px;">
  50       <p><small>Distributed under the Boost Software License, Version 1.0. (See
  51           accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
  52           or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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