1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> 7<title>The MPL Reference Manual: count</title> 8<link rel="stylesheet" href="../style.css" type="text/css" /> 9</head> 10<body class="docframe refmanual"> 11<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./contains.html" class="navigation-link">Prev</a> <a href="./count-if.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./contains.html" class="navigation-link">Back</a> <a href="./count-if.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./querying-algorithms.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 12<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./algorithms.html" class="navigation-link">Algorithms</a> / <a href="./querying-algorithms.html" class="navigation-link">Querying Algorithms</a> / <a href="./count.html" class="navigation-link">count</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="count"> 15<h1><a class="toc-backref" href="./querying-algorithms.html#id1478">count</a></h1> 16<div class="section" id="id559"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename Sequence 21 , typename T 22 > 23struct <a href="./count.html" class="identifier">count</a> 24{ 25 typedef <em>unspecified</em> type; 26}; 27</pre> 28</div> 29<div class="section" id="id560"> 30<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 31<p>Returns the number of elements in a <tt class="literal"><span class="pre">Sequence</span></tt> that are identical to <tt class="literal"><span class="pre">T</span></tt>.</p> 32</div> 33<div class="section" id="id561"> 34<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 35<pre class="literal-block"> 36#include <<a href="../../../../boost/mpl/count.hpp" class="header">boost/mpl/count.hpp</a>> 37</pre> 38</div> 39<div class="section" id="id562"> 40<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> 41<table border="1" class="docutils table"> 42<colgroup> 43<col width="19%" /> 44<col width="35%" /> 45<col width="45%" /> 46</colgroup> 47<thead valign="bottom"> 48<tr><th class="head">Parameter</th> 49<th class="head">Requirement</th> 50<th class="head">Description</th> 51</tr> 52</thead> 53<tbody valign="top"> 54<tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td> 55<td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td> 56<td>A sequence to be examined.</td> 57</tr> 58<tr><td><tt class="literal"><span class="pre">T</span></tt></td> 59<td>Any type</td> 60<td>A type to search for.</td> 61</tr> 62</tbody> 63</table> 64</div> 65<div class="section" id="id563"> 66<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 67<p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt> and arbitrary type <tt class="literal"><span class="pre">t</span></tt>:</p> 68<pre class="literal-block"> 69typedef <a href="./count.html" class="identifier">count</a><s,t>::type n; 70</pre> 71<table class="docutils field-list" frame="void" rules="none"> 72<col class="field-name" /> 73<col class="field-body" /> 74<tbody valign="top"> 75<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</p> 76</td> 77</tr> 78<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> 79<pre class="last literal-block"> 80typedef <a href="./count-if.html" class="identifier">count_if</a>< s,is_same<_,T> >::type n; 81</pre> 82</td> 83</tr> 84</tbody> 85</table> 86</div> 87<div class="section" id="id564"> 88<h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> 89<p>Linear. Exactly <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><s>::value</span></tt> comparisons for identity.</p> 90</div> 91<div class="section" id="id565"> 92<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 93<pre class="literal-block"> 94typedef <a href="./vector.html" class="identifier">vector</a><int,char,long,short,char,short,double,long> types; 95typedef <a href="./count.html" class="identifier">count</a><types, short>::type n; 96 97<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( n::value, ==, 2 ); 98</pre> 99</div> 100<div class="section" id="id566"> 101<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 102<p><a class="reference internal" href="./querying-algorithms.html">Querying Algorithms</a>, <a class="reference internal" href="./count-if.html">count_if</a>, <a class="reference internal" href="./find.html">find</a>, <a class="reference internal" href="./find-if.html">find_if</a>, <a class="reference internal" href="./contains.html">contains</a>, <a class="reference internal" href="./lower-bound.html">lower_bound</a></p> 103<!-- Algorithms/Querying Algorithms//count_if |50 --> 104</div> 105</div> 106 107<div class="footer-separator"></div> 108<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./contains.html" class="navigation-link">Prev</a> <a href="./count-if.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./contains.html" class="navigation-link">Back</a> <a href="./count-if.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./querying-algorithms.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 109<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 110Distributed under the Boost Software License, Version 1.0. (See accompanying 111file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> 112</html> 113