1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>count</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Range 2.0"> 8<link rel="up" href="../non_mutating.html" title="Non-mutating algorithms"> 9<link rel="prev" href="binary_search.html" title="binary_search"> 10<link rel="next" href="count_if.html" title="count_if"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="binary_search.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../non_mutating.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="count_if.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="range.reference.algorithms.non_mutating.count"></a><a class="link" href="count.html" title="count">count</a> 28</h5></div></div></div> 29<h6> 30<a name="range.reference.algorithms.non_mutating.count.h0"></a> 31 <span class="phrase"><a name="range.reference.algorithms.non_mutating.count.prototype"></a></span><a class="link" href="count.html#range.reference.algorithms.non_mutating.count.prototype">Prototype</a> 32 </h6> 33<p> 34</p> 35<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">SinglePassRange</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Value</span><span class="special">></span> 36<span class="keyword">typename</span> <span class="identifier">range_difference</span><span class="special"><</span><span class="identifier">SinglePassRange</span><span class="special">>::</span><span class="identifier">type</span> 37<span class="identifier">count</span><span class="special">(</span><span class="identifier">SinglePassRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">Value</span><span class="special">&</span> <span class="identifier">val</span><span class="special">);</span> 38 39<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">SinglePassRange</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Value</span><span class="special">></span> 40<span class="keyword">typename</span> <span class="identifier">range_difference</span><span class="special"><</span><span class="keyword">const</span> <span class="identifier">SinglePassRange</span><span class="special">>::</span><span class="identifier">type</span> 41<span class="identifier">count</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">SinglePassRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">Value</span><span class="special">&</span> <span class="identifier">val</span><span class="special">);</span> 42</pre> 43<p> 44 </p> 45<h6> 46<a name="range.reference.algorithms.non_mutating.count.h1"></a> 47 <span class="phrase"><a name="range.reference.algorithms.non_mutating.count.description"></a></span><a class="link" href="count.html#range.reference.algorithms.non_mutating.count.description">Description</a> 48 </h6> 49<p> 50 <code class="computeroutput"><span class="identifier">count</span></code> returns the number 51 of elements <code class="computeroutput"><span class="identifier">x</span></code> in <code class="computeroutput"><span class="identifier">rng</span></code> where <code class="computeroutput"><span class="identifier">x</span> 52 <span class="special">==</span> <span class="identifier">val</span></code> 53 is <code class="computeroutput"><span class="keyword">true</span></code>. 54 </p> 55<h6> 56<a name="range.reference.algorithms.non_mutating.count.h2"></a> 57 <span class="phrase"><a name="range.reference.algorithms.non_mutating.count.definition"></a></span><a class="link" href="count.html#range.reference.algorithms.non_mutating.count.definition">Definition</a> 58 </h6> 59<p> 60 Defined in the header file <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">range</span><span class="special">/</span><span class="identifier">algorithm</span><span class="special">/</span><span class="identifier">count</span><span class="special">.</span><span class="identifier">hpp</span></code> 61 </p> 62<h6> 63<a name="range.reference.algorithms.non_mutating.count.h3"></a> 64 <span class="phrase"><a name="range.reference.algorithms.non_mutating.count.requirements"></a></span><a class="link" href="count.html#range.reference.algorithms.non_mutating.count.requirements">Requirements</a> 65 </h6> 66<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 67<li class="listitem"> 68 <code class="computeroutput"><span class="identifier">SinglePassRange</span></code> is 69 a model of the <a class="link" href="../../../concepts/single_pass_range.html" title="Single Pass Range">Single 70 Pass Range</a> Concept. 71 </li> 72<li class="listitem"> 73 <code class="computeroutput"><span class="identifier">Value</span></code> is a model 74 of the <code class="computeroutput"><span class="identifier">EqualityComparableConcept</span></code>. 75 </li> 76<li class="listitem"> 77 <code class="computeroutput"><span class="identifier">SinglePassRange</span></code>'s 78 value type is a model of the <code class="computeroutput"><span class="identifier">EqualityComparableConcept</span></code>. 79 </li> 80<li class="listitem"> 81 An object of <code class="computeroutput"><span class="identifier">SinglePassRange</span></code>'s 82 value type can be compared for equality with an object of type <code class="computeroutput"><span class="identifier">Value</span></code>. 83 </li> 84</ul></div> 85<h6> 86<a name="range.reference.algorithms.non_mutating.count.h4"></a> 87 <span class="phrase"><a name="range.reference.algorithms.non_mutating.count.complexity"></a></span><a class="link" href="count.html#range.reference.algorithms.non_mutating.count.complexity">Complexity</a> 88 </h6> 89<p> 90 Linear. Exactly <code class="computeroutput"><span class="identifier">distance</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)</span></code> comparisons. 91 </p> 92</div> 93<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 94<td align="left"></td> 95<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 96 Neil Groves<p> 97 Distributed under the Boost Software License, Version 1.0. (See accompanying 98 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 99 </p> 100</div></td> 101</tr></table> 102<hr> 103<div class="spirit-nav"> 104<a accesskey="p" href="binary_search.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../non_mutating.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="count_if.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 105</div> 106</body> 107</html> 108
