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  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="the_boost_algorithm_library.Misc.find_not"></a><a class="link" href="find_not.html" title="find_not">find_not
  28       </a>
  29 </h3></div></div></div>
  30 <p>
  31         The header file 'find_not.hpp' contains a variants of a the stl algorithm
  32         <code class="computeroutput"><span class="identifier">find</span></code>. The algorithm finds
  33         the first value in the given sequence that is not equal to the given value.
  34       </p>
  35 <p>
  36         Consider this use of <code class="computeroutput"><span class="identifier">find</span><span class="special">()</span></code>:
  37       </p>
  38 <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">vec</span> <span class="special">=</span> <span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span> <span class="special">};</span>
  39 <span class="keyword">auto</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">find</span><span class="special">(</span><span class="identifier">vec</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">vec</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="number">1</span><span class="special">);</span>
  40 </pre>
  41 <p>
  42         This gives us the first occurance of <code class="computeroutput"><span class="number">1</span></code>
  43         in <code class="computeroutput"><span class="identifier">vec</span></code>. What if we want to
  44         find the first occurrance of any number besides <code class="computeroutput"><span class="number">1</span></code>
  45         in <code class="computeroutput"><span class="identifier">vec</span></code>? We have to write
  46         an unfortunate amount of code:
  47       </p>
  48 <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">vec</span> <span class="special">=</span> <span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span> <span class="special">};</span>
  49 <span class="keyword">auto</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">find_if</span><span class="special">(</span><span class="identifier">vec</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">vec</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="special">[](</span><span class="keyword">int</span> <span class="identifier">i</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">i</span> <span class="special">!=</span> <span class="number">1</span><span class="special">;</span> <span class="special">});</span>
  50 </pre>
  51 <p>
  52         With <code class="computeroutput"><span class="identifier">find_not</span><span class="special">()</span></code>
  53         the code gets much more terse:
  54       </p>
  55 <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">vec</span> <span class="special">=</span> <span class="special">{</span> <span class="number">1</span><span class="special">,</span> <span class="number">1</span><span class="special">,</span> <span class="number">2</span> <span class="special">};</span>
  56 <span class="keyword">auto</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">find_not</span><span class="special">(</span><span class="identifier">vec</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">vec</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="number">1</span><span class="special">);</span>
  57 </pre>
  58 <p>
  59         The existing <code class="computeroutput"><span class="identifier">find</span></code> variants
  60         are: <code class="computeroutput"><span class="identifier">find</span><span class="special">()</span></code>,
  61         <code class="computeroutput"><span class="identifier">find_if</span><span class="special">()</span></code>,
  62         and <code class="computeroutput"><span class="identifier">find_if_not</span><span class="special">()</span></code>.
  63         It seems natural to also have <code class="computeroutput"><span class="identifier">find_not</span><span class="special">()</span></code>, for the very reason that we have <code class="computeroutput"><span class="identifier">find_if_not</span><span class="special">()</span></code>
  64         -- to avoid having to write a lambda to wrap the negation of the find condition.
  65       </p>
  66 <h5>
  67 <a name="the_boost_algorithm_library.Misc.find_not.h0"></a>
  68         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.interface"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.interface">interface</a>
  69       </h5>
  70 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">InputIter</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Sentinel</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  71 <span class="identifier">InputIter</span> <span class="identifier">find_not</span><span class="special">(</span><span class="identifier">InputIter</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">Sentinel</span> <span class="identifier">last</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&amp;</span> <span class="identifier">x</span><span class="special">);</span>
  72
  73 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Range</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  74 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="identifier">Range</span><span class="special">&gt;</span> <span class="identifier">find_not</span><span class="special">(</span><span class="identifier">Range</span> <span class="special">&amp;</span> <span class="identifier">r</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&amp;</span> <span class="identifier">x</span><span class="special">);</span>
  75 </pre>
  76 <p>
  77         These overloads of <code class="computeroutput"><span class="identifier">find_not</span></code>
  78         return the first value that is not equal to <code class="computeroutput"><span class="identifier">x</span></code>
  79         in the sequence <code class="computeroutput"><span class="special">[</span><span class="identifier">first</span><span class="special">,</span> <span class="identifier">last</span><span class="special">)</span></code> or <code class="computeroutput"><span class="identifier">r</span></code>,
  80         respectively.
  81       </p>
  82 <h5>
  83 <a name="the_boost_algorithm_library.Misc.find_not.h1"></a>
  84         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.examples"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.examples">Examples</a>
  85       </h5>
  86 <p>
  87         Given the container <code class="computeroutput"><span class="identifier">c1</span></code> containing
  88         <code class="computeroutput"><span class="special">{</span> <span class="number">0</span><span class="special">,</span> <span class="number">1</span><span class="special">,</span>
  89         <span class="number">2</span> <span class="special">}</span></code>,
  90         then
  91       </p>
  92 <pre class="programlisting"><span class="identifier">find_not</span> <span class="special">(</span> <span class="identifier">c1</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span>     <span class="identifier">c1</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span>    <span class="number">1</span> <span class="special">)</span> <span class="special">--&gt;</span> <span class="identifier">c1</span><span class="special">.</span><span class="identifier">begin</span><span class="special">()</span>
  93 <span class="identifier">find_not</span> <span class="special">(</span> <span class="identifier">c1</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span>     <span class="identifier">c1</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span>    <span class="number">0</span> <span class="special">)</span> <span class="special">--&gt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">next</span><span class="special">(</span><span class="identifier">c1</span><span class="special">.</span><span class="identifier">begin</span><span class="special">())</span>
  94 </pre>
  95 <h5>
  96 <a name="the_boost_algorithm_library.Misc.find_not.h2"></a>
  97         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.iterator_requirements"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.iterator_requirements">Iterator
  98         Requirements</a>
  99       </h5>
 100 <p>
 101         <code class="computeroutput"><span class="identifier">find_not</span></code> works on all iterators
 102         except output iterators.
 103       </p>
 104 <p>
 105         The template parameter <code class="computeroutput"><span class="identifier">Sentinel</span></code>
 106         is allowed to be different from <code class="computeroutput"><span class="identifier">InputIter</span></code>,
 107         or they may be the same. For an <code class="computeroutput"><span class="identifier">InputIter</span></code>
 108         <code class="computeroutput"><span class="identifier">it</span></code> and a <code class="computeroutput"><span class="identifier">Sentinel</span></code>
 109         <code class="computeroutput"><span class="identifier">end</span></code>, <code class="computeroutput"><span class="identifier">it</span>
 110         <span class="special">==</span> <span class="identifier">end</span></code>
 111         and <code class="computeroutput"><span class="identifier">it</span> <span class="special">!=</span>
 112         <span class="identifier">end</span></code> must be well-formed expressions.
 113       </p>
 114 <h5>
 115 <a name="the_boost_algorithm_library.Misc.find_not.h3"></a>
 116         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.complexity"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.complexity">Complexity</a>
 117       </h5>
 118 <p>
 119         Linear.
 120       </p>
 121 <h5>
 122 <a name="the_boost_algorithm_library.Misc.find_not.h4"></a>
 123         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.exception_safety"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.exception_safety">Exception
 124         Safety</a>
 125       </h5>
 126 <p>
 127         <code class="computeroutput"><span class="identifier">find_not</span></code> takes its parameters
 128         by value and do not depend upon any global state. Therefore, it provides
 129         the strong exception guarantee.
 130       </p>
 131 <h5>
 132 <a name="the_boost_algorithm_library.Misc.find_not.h5"></a>
 133         <span class="phrase"><a name="the_boost_algorithm_library.Misc.find_not.notes"></a></span><a class="link" href="find_not.html#the_boost_algorithm_library.Misc.find_not.notes">Notes</a>
 134       </h5>
 135 <p>
 136         <code class="computeroutput"><span class="keyword">constexpr</span></code> in C++14 or later.
 137       </p>
 138 </div>
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 143         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>)
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