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<H2>find_if()</H2>
<P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-9.html">Algorithms</A></P>

<PRE><HR><B><I>Function</I></B><HR></PRE>

<UL>
<LI><A HREF="#sec1">Local Index</A></LI>
<LI><A HREF="#sec2">Summary</A></LI>
<LI><A HREF="#sec3">Synopsis</A></LI>
<LI><A HREF="#sec4">Description</A></LI>
<LI><A HREF="#sec5">Complexity</A></LI>
<LI><A HREF="#sec6">Example</A></LI>
<LI><A HREF="#sec7">See Also</A></LI>
<LI><A HREF="#sec8">Standards Conformance</A></LI>
</UL>
<A NAME="sec1"><H3>Local Index</H3></A>
No Entries
<A NAME="sec2"><H3>Summary</H3></A>
<P>Algorithm that finds an occurrence of a value in a sequence that satisfies a specified predicate</P>
<A NAME="sec3"><H3>Synopsis</H3></A>

<PRE>#include &lt;algorithm&gt;

namespace std {
  template &lt;class InputIterator, class Predicate&gt;
  InputIterator find_if(InputIterator start,
                        InputIterator finish,
                        Predicate pred);
}
</PRE>
<A NAME="sec4"><H3>Description</H3></A>
<P>The <SAMP>find_if()</SAMP> algorithm allows you to search for the first element in a sequence that satisfies a particular condition. The sequence is defined by iterators <SAMP>start</SAMP> and <SAMP>finish</SAMP>, while the condition is defined by the third argument: a predicate function that returns a boolean value. <SAMP>find_if()</SAMP> returns the first iterator <SAMP>i</SAMP> in the range <SAMP>[start, finish)</SAMP> for which the following condition holds:</P>
<P><SAMP>pred(*i) == true.</SAMP></P>
<P>If no such iterator is found, <SAMP>find_if()</SAMP> returns <SAMP>finish</SAMP>.</P>
<A NAME="sec5"><H3>Complexity</H3></A>
<P><SAMP>find_if()</SAMP> performs at most <SAMP>finish-start</SAMP> applications of the corresponding predicate.</P>
<A NAME="sec6"><H3>Example</H3></A>

<UL><PRE>//
//  find.cpp
//

#include &lt;vector&gt;      // for vector
#include &lt;algorithm&gt;   // for adjacent_find, find
#include &lt;functional&gt;  // for bind1st, equal_to
#include &lt;iostream&gt;    // for cout, endl


int main ()
{
    // Typedef for convenience.
    typedef std::vector&lt;int, std::allocator&lt;int&gt; &gt; Vector;

    const Vector::value_type arr[] = { 0, 1, 2, 2, 3, 
                                       4, 2, 2, 6, 7 };

    // Set up a vector.
    const Vector v1 (arr, arr + sizeof arr / sizeof *arr);

    // Try find.
    Vector::const_iterator it = std::find (v1.begin (), 
                                           v1.end (), 3);

    std::cout &lt;&lt; *it &lt;&lt; ' ';

    // Try find_if.
    it = std::find_if (v1.begin (), v1.end (),
             std::bind1st (std::equal_to&lt;Vector::value_type&gt;(), 
             3));

    std::cout &lt;&lt; *it &lt;&lt; ' ';

    // Try both adjacent_find variants.
    it = std::adjacent_find (v1.begin (), v1.end ());

    std::cout &lt;&lt; *it &lt;&lt; ' ';

    it = std::adjacent_find (v1.begin (), v1.end (),
                          std::equal_to&lt;Vector::value_type&gt;());

    std::cout &lt;&lt; *it &lt;&lt; std::endl;

    return 0;
}


Program Output:
</PRE></UL>
<UL><PRE>3 3 2 2
</PRE></UL>
<A NAME="sec7"><H3>See Also</H3></A>
<P><SAMP><A HREF="adjacent-find.html">adjacent_find()</A></SAMP>, <A HREF="algorithms.html">Algorithms</A>, <SAMP><A HREF="find.html">find()</A></SAMP>, <SAMP><A HREF="find-end.html">find_end()</A></SAMP>, <SAMP><A HREF="find-first-of.html">find_first_of()</A></SAMP></P>
<A NAME="sec8"><H3>Standards Conformance</H3></A>
<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.1.2</I></P>

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