1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>filtered</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="../reference.html" title="Reference"> 9<link rel="prev" href="copied.html" title="copied"> 10<link rel="next" href="indexed.html" title="indexed"> 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="copied.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="indexed.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.adaptors.reference.filtered"></a><a class="link" href="filtered.html" title="filtered">filtered</a> 28</h5></div></div></div> 29<div class="toc"><dl class="toc"><dt><span class="section"><a href="filtered.html#range.reference.adaptors.reference.filtered.filtered_example">filtered 30 example</a></span></dt></dl></div> 31<div class="informaltable"><table class="table"> 32<colgroup> 33<col> 34<col> 35</colgroup> 36<thead><tr> 37<th> 38 <p> 39 Syntax 40 </p> 41 </th> 42<th> 43 <p> 44 Code 45 </p> 46 </th> 47</tr></thead> 48<tbody> 49<tr> 50<td> 51 <p> 52 Pipe 53 </p> 54 </td> 55<td> 56 <p> 57 <code class="computeroutput"><span class="identifier">rng</span> <span class="special">|</span> 58 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">filtered</span><span class="special">(</span><span class="identifier">pred</span><span class="special">)</span></code> 59 </p> 60 </td> 61</tr> 62<tr> 63<td> 64 <p> 65 Function 66 </p> 67 </td> 68<td> 69 <p> 70 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">filter</span><span class="special">(</span><span class="identifier">rng</span><span class="special">,</span> 71 <span class="identifier">pred</span><span class="special">)</span></code> 72 </p> 73 </td> 74</tr> 75</tbody> 76</table></div> 77<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 78<li class="listitem"> 79 <span class="bold"><strong>Precondition:</strong></span> The <code class="computeroutput"><span class="identifier">value_type</span></code> of the range is convertible 80 to the argument type of <code class="computeroutput"><span class="identifier">pred</span></code>. 81 </li> 82<li class="listitem"> 83 <span class="bold"><strong>Postcondition:</strong></span> For all elements 84 <code class="computeroutput"><span class="special">[</span><span class="identifier">x</span><span class="special">]</span></code> in the returned range, <code class="computeroutput"><span class="identifier">pred</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code> 85 is <code class="computeroutput"><span class="keyword">true</span></code>. 86 </li> 87<li class="listitem"> 88 <span class="bold"><strong>Throws:</strong></span> Whatever the copy constructor 89 of <code class="computeroutput"><span class="identifier">pred</span></code> might throw. 90 </li> 91<li class="listitem"> 92 <span class="bold"><strong>Range Category:</strong></span> __singlepass_range__ 93 </li> 94<li class="listitem"> 95 <span class="bold"><strong>Range Return Type:</strong></span> <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">filtered_range</span><span class="special"><</span><span class="keyword">decltype</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)></span></code> 96 </li> 97<li class="listitem"> 98 <span class="bold"><strong>Returned Range Category:</strong></span> The minimum 99 of the range category of <code class="computeroutput"><span class="identifier">rng</span></code> 100 and <a class="link" href="../../../concepts/bidirectional_range.html" title="Bidirectional Range">Bidirectional 101 Range</a> 102 </li> 103</ul></div> 104<div class="section"> 105<div class="titlepage"><div><div><h6 class="title"> 106<a name="range.reference.adaptors.reference.filtered.filtered_example"></a><a class="link" href="filtered.html#range.reference.adaptors.reference.filtered.filtered_example" title="filtered example">filtered 107 example</a> 108</h6></div></div></div> 109<p> 110</p> 111<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">range</span><span class="special">/</span><span class="identifier">adaptor</span><span class="special">/</span><span class="identifier">filtered</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 112<span class="preprocessor">#include</span> <span class="special"><</span><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">copy</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 113<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">assign</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 114<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iterator</span><span class="special">></span> 115<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 116<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> 117 118<span class="keyword">struct</span> <span class="identifier">is_even</span> 119<span class="special">{</span> 120 <span class="keyword">bool</span> <span class="keyword">operator</span><span class="special">()(</span> <span class="keyword">int</span> <span class="identifier">x</span> <span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">x</span> <span class="special">%</span> <span class="number">2</span> <span class="special">==</span> <span class="number">0</span><span class="special">;</span> <span class="special">}</span> 121<span class="special">};</span> 122 123<span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">argc</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">argv</span><span class="special">[])</span> 124<span class="special">{</span> 125 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">assign</span><span class="special">;</span> 126 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">;</span> 127 128 <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">input</span><span class="special">;</span> 129 <span class="identifier">input</span> <span class="special">+=</span> <span class="number">1</span><span class="special">,</span><span class="number">2</span><span class="special">,</span><span class="number">3</span><span class="special">,</span><span class="number">4</span><span class="special">,</span><span class="number">5</span><span class="special">,</span><span class="number">6</span><span class="special">,</span><span class="number">7</span><span class="special">,</span><span class="number">8</span><span class="special">,</span><span class="number">9</span><span class="special">;</span> 130 131 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">copy</span><span class="special">(</span> 132 <span class="identifier">input</span> <span class="special">|</span> <span class="identifier">filtered</span><span class="special">(</span><span class="identifier">is_even</span><span class="special">()),</span> 133 <span class="identifier">std</span><span class="special">::</span><span class="identifier">ostream_iterator</span><span class="special"><</span><span class="keyword">int</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special">,</span> <span class="string">","</span><span class="special">));</span> 134 135 <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> 136<span class="special">}</span> 137</pre> 138<p> 139 </p> 140</div> 141<p> 142 This would produce the output: 143</p> 144<pre class="programlisting"><span class="number">2</span><span class="special">,</span><span class="number">4</span><span class="special">,</span><span class="number">6</span><span class="special">,</span><span class="number">8</span><span class="special">,</span> 145</pre> 146<p> 147 </p> 148</div> 149<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 150<td align="left"></td> 151<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 152 Neil Groves<p> 153 Distributed under the Boost Software License, Version 1.0. (See accompanying 154 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>) 155 </p> 156</div></td> 157</tr></table> 158<hr> 159<div class="spirit-nav"> 160<a accesskey="p" href="copied.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="indexed.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 161</div> 162</body> 163</html> 164
