1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>find_if</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="find_first_of.html" title="find_first_of"> 10<link rel="next" href="lexicographical_compare.html" title="lexicographical_compare"> 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="find_first_of.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="lexicographical_compare.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.find_if"></a><a class="link" href="find_if.html" title="find_if">find_if</a> 28</h5></div></div></div> 29<h6> 30<a name="range.reference.algorithms.non_mutating.find_if.h0"></a> 31 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.prototype"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.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">UnaryPredicate</span><span class="special">></span> 36<span class="keyword">typename</span> <span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">SinglePassRange</span><span class="special">>::</span><span class="identifier">type</span> 37<span class="identifier">find_if</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="identifier">UnaryPredicate</span> <span class="identifier">pred</span><span class="special">);</span> 38 39<span class="keyword">template</span><span class="special"><</span> 40 <span class="identifier">range_return_value</span> <span class="identifier">re</span><span class="special">,</span> 41 <span class="keyword">class</span> <span class="identifier">SinglePassRange</span><span class="special">,</span> 42 <span class="keyword">class</span> <span class="identifier">UnaryPredicate</span> 43 <span class="special">></span> 44<span class="keyword">typename</span> <span class="identifier">range_return</span><span class="special"><</span><span class="identifier">SinglePassRange</span><span class="special">,</span> <span class="identifier">re</span><span class="special">>::</span><span class="identifier">type</span> 45<span class="identifier">find_if</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="identifier">UnaryPredicate</span> <span class="identifier">pred</span><span class="special">);</span> 46</pre> 47<p> 48 </p> 49<h6> 50<a name="range.reference.algorithms.non_mutating.find_if.h1"></a> 51 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.description"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.description">Description</a> 52 </h6> 53<p> 54 The versions of <code class="computeroutput"><span class="identifier">find_if</span></code> 55 that return an iterator, returns the first iterator in the range <code class="computeroutput"><span class="identifier">rng</span></code> such that <code class="computeroutput"><span class="identifier">pred</span><span class="special">(*</span><span class="identifier">i</span><span class="special">)</span></code> is <code class="computeroutput"><span class="keyword">true</span></code>. 56 <code class="computeroutput"><span class="identifier">end</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)</span></code> 57 is returned if no such iterator exists. 58 </p> 59<p> 60 The versions of <code class="computeroutput"><span class="identifier">find_if</span></code> 61 that return a <code class="computeroutput"><span class="identifier">range_return</span></code>, 62 defines found in the same manner as the returned iterator described above. 63 </p> 64<h6> 65<a name="range.reference.algorithms.non_mutating.find_if.h2"></a> 66 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.definition"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.definition">Definition</a> 67 </h6> 68<p> 69 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">find_if</span><span class="special">.</span><span class="identifier">hpp</span></code> 70 </p> 71<h6> 72<a name="range.reference.algorithms.non_mutating.find_if.h3"></a> 73 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.requirements"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.requirements">Requirements</a> 74 </h6> 75<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 76<li class="listitem"> 77 <code class="computeroutput"><span class="identifier">SinglePassRange</span></code> is 78 a model of the <a class="link" href="../../../concepts/single_pass_range.html" title="Single Pass Range">Single 79 Pass Range</a> Concept. 80 </li> 81<li class="listitem"> 82 <code class="computeroutput"><span class="identifier">UnaryPredicate</span></code> is 83 a model of the <code class="computeroutput"><span class="identifier">PredicateConcept</span></code>. 84 </li> 85<li class="listitem"> 86 The value type of <code class="computeroutput"><span class="identifier">SinglePassRange</span></code> 87 is convertible to the argument type of <code class="computeroutput"><span class="identifier">UnaryPredicate</span></code>. 88 </li> 89</ul></div> 90<h6> 91<a name="range.reference.algorithms.non_mutating.find_if.h4"></a> 92 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.precondition_"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.precondition_">Precondition:</a> 93 </h6> 94<p> 95 For each iterator <code class="computeroutput"><span class="identifier">i</span></code> in 96 <code class="computeroutput"><span class="identifier">rng</span></code>, <code class="computeroutput"><span class="special">*</span><span class="identifier">i</span></code> is in the domain of <code class="computeroutput"><span class="identifier">UnaryPredicate</span></code>. 97 </p> 98<h6> 99<a name="range.reference.algorithms.non_mutating.find_if.h5"></a> 100 <span class="phrase"><a name="range.reference.algorithms.non_mutating.find_if.complexity"></a></span><a class="link" href="find_if.html#range.reference.algorithms.non_mutating.find_if.complexity">Complexity</a> 101 </h6> 102<p> 103 Linear. At most <code class="computeroutput"><span class="identifier">distance</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)</span></code> invocations of <code class="computeroutput"><span class="identifier">pred</span></code>. 104 </p> 105</div> 106<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 107<td align="left"></td> 108<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 109 Neil Groves<p> 110 Distributed under the Boost Software License, Version 1.0. (See accompanying 111 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>) 112 </p> 113</div></td> 114</tr></table> 115<hr> 116<div class="spirit-nav"> 117<a accesskey="p" href="find_first_of.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="lexicographical_compare.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 118</div> 119</body> 120</html> 121
