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58 lines
2.6 KiB
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58 lines
2.6 KiB
HTML
<!doctype html public "-//ietf//dtd html//en">
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<html><head><title>boost::mpl::find_if</title>
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<link rel="stylesheet" href="../mpl_wiki.css">
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</head><body bgcolor="white">
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<h1><a href="../Table_of_Contents.html"><img src="../mpl_logo.jpg" alt="[Home]" border=0 align="right"></a>find_if</h1><h3>Synopsis</h3>
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<p>
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<pre>
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template<
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typename Sequence
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, typename Pred
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>
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struct find_if
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{
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typedef <em>unspecified</em> type;
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};
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</pre>
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<p>
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<h3>Description</h3>
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<p>
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Finds the first element in a <code>Sequence</code> that satisfies the predicate <code>Pred</code>.
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<p>
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<h3>Definition</h3>
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<p>
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<pre>
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#include "<a href="../../../../../boost/mpl/find_if.hpp">boost/mpl/find_if.hpp</a>"
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</pre>
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<p>
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<h3>Parameters</h3>
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<table border="1">
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<tr><th> Parameter </th><th> Requirement </th><th> Description </th></tr>
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<tr><td><code>Sequence</code></td><td>A model of <a href="../Forward_Sequence.html">Forward Sequence</a></td><td>A sequence to search in. </td></tr>
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<tr><td><code>Pred</code></td><td>A model of Predicate [Lambda Expression]</td><td>A search condition. </td></tr>
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</table>
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<p>
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<h3>Expression semantics</h3>
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<p>
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<table border="1">
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<tr><th> Expression </th><th> Expression type </th><th> Precondition </th><th> Semantics </th><th> Postcondition </th></tr>
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<tr><td><code>typedef find_if<Sequence,Pred>::type i;</code></td><td>A model of <a href="../Forward_Iterator.html">Forward Iterator</a></td><td></td><td><code>i</code> is the first iterator in the range <code>[begin<Sequence>::type, end<Sequence>::type)</code> such that <code>apply< lambda<Pred>::type,i::type >::type::value == true</code>; <code>i</code> is identical to <code>end<Sequence>::type</code>, if no such iterator exists.</td><td></td></tr>
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</table>
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<p>
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<h3>Complexity</h3>
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<p>
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Linear. At most <code>size<Sequence>::value</code> applications of <code>Pred</code>.
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<p>
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<h3>Example</h3>
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<p>
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<pre>
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typedef <a href="../Reference/vector.html">vector</a><char,int,unsigned,long,unsigned_long> types;
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typedef find_if<types, is_same<_1,unsigned> >::type iter;
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BOOST_STATIC_ASSERT(iter::pos::value == 2);
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</pre>
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<p>
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<h3>See also</h3>
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<p>
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<a href="../Algorithms.html">Algorithms</a>, <code><a href="../Reference/find.html">find</a></code>, <code><a href="../Reference/contains.html">contains</a></code>, <code><a href="../Reference/count.html">count</a></code>, <code><a href="../Reference/count_if.html">count_if</a></code>
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<p><hr>
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<a href="../Table_of_Contents.html">Table of Contents</a><br>Last edited September 15, 2002 7:24 pm</body></html> |