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  26 <a name="boost.sort.spreadsort.reverse_string_idp23645040"></a><div class="titlepage"></div>
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  28 <h2><span class="refentrytitle">Function template reverse_string_sort</span></h2>
  29 <p>boost::sort::spreadsort::reverse_string_sort &#8212; String sort algorithm using random access iterators, allowing character-type overloads. </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../../header/boost/sort/spreadsort/string_sort_hpp.html" title="Header &lt;boost/sort/spreadsort/string_sort.hpp&gt;">boost/sort/spreadsort/string_sort.hpp</a>&gt;
  33
  34 </span>
  35 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> RandomAccessIter<span class="special">,</span> <span class="keyword">typename</span> Compare<span class="special">,</span>
  36          <span class="keyword">typename</span> Unsigned_char_type<span class="special">&gt;</span>
  37   <span class="keyword">void</span> <span class="identifier">reverse_string_sort</span><span class="special">(</span><span class="identifier">RandomAccessIter</span> first<span class="special">,</span> <span class="identifier">RandomAccessIter</span> last<span class="special">,</span>
  38                            <span class="identifier">Compare</span> comp<span class="special">,</span> <span class="identifier">Unsigned_char_type</span> unused<span class="special">)</span><span class="special">;</span></pre></div>
  39 <div class="refsect1">
  40 <a name="idp79094288"></a><h2>Description</h2>
  41 <p>(All variants fall back to <code class="computeroutput">std::sort</code> if the data size is too small, &lt; detail::min_sort_size).</p>
  42 <p><code class="computeroutput">integer_sort</code> is a fast templated in-place hybrid radix/comparison algorithm, which in testing tends to be roughly 50% to 2X faster than <code class="computeroutput">std::sort</code> for large tests (&gt;=100kB).<br>
  43 Worst-case performance is <span class="emphasis"><em> O(N * (lg(range)/s + s)) </em></span>, so <code class="computeroutput">integer_sort</code> is asymptotically faster than pure comparison-based algorithms. <code class="computeroutput">s</code> is <code class="computeroutput">max_splits</code>, which defaults to 11, so its worst-case with default settings for 32-bit integers is <span class="emphasis"><em> O(N * ((32/11) </em></span> slow radix-based iterations fast comparison-based iterations).<br>
  44 <br>
  45 Some performance plots of runtime vs. n and log(range) are provided:<br>
  46  <a href="../../../../../doc/graph/windows_integer_sort.htm" target="_top">windows_integer_sort</a> <br>
  47  <a href="../../../../../doc/graph/osx_integer_sort.htm" target="_top">osx_integer_sort</a></p>
  48 <p>
  49
  50
  51
  52
  53
  54 </p>
  55 <div class="warning"><table border="0" summary="Warning">
  56 <tr>
  57 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../../../../../doc/src/images/warning.png"></td>
  58 <th align="left">Warning</th>
  59 </tr>
  60 <tr><td align="left" valign="top">
  61 <p>Throwing an exception may cause data loss. This will also throw if a small vector resize throws, in which case there will be no data loss. </p>
  62 <p>Invalid arguments cause undefined behaviour. </p>
  63 </td></tr>
  64 </table></div>
  65 <p>
  66 </p>
  67 <div class="note"><table border="0" summary="Note">
  68 <tr>
  69 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../doc/src/images/note.png"></td>
  70 <th align="left">Note</th>
  71 </tr>
  72 <tr><td align="left" valign="top"><p><code class="computeroutput">spreadsort</code> function provides a wrapper that calls the fastest sorting algorithm available for a data type, enabling faster generic-programming.</p></td></tr>
  73 </table></div>
  74 <p>
  75 </p>
  76 <p>The lesser of <span class="emphasis"><em> O(N*log(N)) </em></span> comparisons and <span class="emphasis"><em> O(N*log(K/S + S)) </em></span>operations worst-case, where: </p>
  77 <p>* N is <code class="computeroutput">last</code> - <code class="computeroutput">first</code>, </p>
  78 <p>* K is the log of the range in bits (32 for 32-bit integers using their full range), </p>
  79 <p>* S is a constant called max_splits, defaulting to 11 (except for strings where it is the log of the character size). </p>
  80 <p>
  81 </p>
  82 <div class="variablelist"><table border="0" class="variablelist compact">
  83 <colgroup>
  84 <col align="left" valign="top">
  85 <col>
  86 </colgroup>
  87 <tbody>
  88 <tr>
  89 <td><p><span class="term">Parameters:</span></p></td>
  90 <td><div class="variablelist"><table border="0" class="variablelist compact">
  91 <colgroup>
  92 <col align="left" valign="top">
  93 <col>
  94 </colgroup>
  95 <tbody>
  96 <tr>
  97 <td><p><span class="term"><code class="computeroutput">comp</code></span></p></td>
  98 <td><p>A binary functor that returns whether the first element passed to it should go before the second in order. </p></td>
  99 </tr>
 100 <tr>
 101 <td><p><span class="term"><code class="computeroutput">first</code></span></p></td>
 102 <td><p>Iterator pointer to first element. </p></td>
 103 </tr>
 104 <tr>
 105 <td><p><span class="term"><code class="computeroutput">last</code></span></p></td>
 106 <td><p>Iterator pointing to one beyond the end of data. </p></td>
 107 </tr>
 108 <tr>
 109 <td><p><span class="term"><code class="computeroutput">unused</code></span></p></td>
 110 <td><p>value with the same type as the result of the [] operator, defining the Unsigned_char_type. The actual value is unused.</p></td>
 111 </tr>
 112 </tbody>
 113 </table></div></td>
 114 </tr>
 115 <tr>
 116 <td><p><span class="term">Template Parameters:</span></p></td>
 117 <td><div class="variablelist"><table border="0" class="variablelist compact">
 118 <colgroup>
 119 <col align="left" valign="top">
 120 <col>
 121 </colgroup>
 122 <tbody>
 123 <tr>
 124 <td><p><span class="term"><code class="computeroutput">RandomAccessIter</code></span></p></td>
 125 <td><p><a href="http://www.cplusplus.com/reference/iterator/RandomAccessIterator/" target="_top">Random access iterator</a> </p></td>
 126 </tr>
 127 <tr>
 128 <td><p><span class="term"><code class="computeroutput">Unsigned_char_type</code></span></p></td>
 129 <td><p>Unsigned character type used for string.</p></td>
 130 </tr>
 131 </tbody>
 132 </table></div></td>
 133 </tr>
 134 <tr>
 135 <td><p><span class="term">Requires:</span></p></td>
 136 <td>
 137 <p>[<code class="computeroutput">first</code>, <code class="computeroutput">last</code>) is a valid range. </p>
 138 <p><code class="computeroutput">RandomAccessIter</code> <code class="computeroutput">value_type</code> is mutable. </p>
 139 <p><code class="computeroutput">RandomAccessIter</code> <code class="computeroutput">value_type</code> is <a href="http://en.cppreference.com/w/cpp/concept/LessThanComparable" target="_top">LessThanComparable</a> </p>
 140 <p><code class="computeroutput">RandomAccessIter</code> <code class="computeroutput">value_type</code> supports the <code class="computeroutput">operator&gt;&gt;</code>, which returns an integer-type right-shifted a specified number of bits. </p>
 141 </td>
 142 </tr>
 143 <tr>
 144 <td><p><span class="term">Postconditions:</span></p></td>
 145 <td><p>The elements in the range [<code class="computeroutput">first</code>, <code class="computeroutput">last</code>) are sorted in ascending order.</p></td>
 146 </tr>
 147 <tr>
 148 <td><p><span class="term">Returns:</span></p></td>
 149 <td><p><code class="computeroutput">void</code>.</p></td>
 150 </tr>
 151 <tr>
 152 <td><p><span class="term">Throws:</span></p></td>
 153 <td>std::exception Propagates exceptions if any of the element comparisons, the element swaps (or moves), the right shift, subtraction of right-shifted elements, functors, or any operations on iterators throw.</td>
 154 </tr>
 155 </tbody>
 156 </table></div>
 157 </div>
 158 </div>
 159 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 160 <td align="left"></td>
 161 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Steven Ross<p>
 162         Distributed under the <a href="http://boost.org/LICENSE_1_0.txt" target="_top">Boost
 163         Software License, Version 1.0</a>.
 164       </p>
 165 </div></td>
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