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 <H2>partition()</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 places all of the entities that satisfy the given predicate before all of the entities that do not</P>
 <A NAME="sec3"><H3>Synopsis</H3></A>

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

 namespace std {
   template &lt;class BidirectionalIterator, class Predicate&gt;
   BidirectionalIterator
   partition(BidirectionalIterator start,
             BidirectionalIterator finish,
             Predicate pred);
 }
 </PRE>
 <A NAME="sec4"><H3>Description</H3></A>
 <P>For the range <SAMP>[start, finish)</SAMP>, the <SAMP>partition()</SAMP> algorithm places all elements that satisfy the predicate <SAMP>pred</SAMP> before all elements that do not satisfy <SAMP>pred</SAMP>. It returns an iterator that is one past the end of the group of elements that satisfy <SAMP>pred</SAMP>. In other words, <SAMP>partition()</SAMP> returns <SAMP>i</SAMP> such that for any iterator <SAMP>j</SAMP> in the range <SAMP>[start, i)</SAMP>, <SAMP>pred(*j) == true</SAMP>, and, for any iterator <SAMP>k</SAMP> in the range <SAMP>[i, finish)</SAMP>, <SAMP>pred(*j) == false</SAMP>.</P>
 <P>Note that <SAMP>partition()</SAMP> does not necessarily maintain the relative order of the elements that match and elements that do not match the predicate. Use the algorithm <SAMP><A HREF="stable-partition.html">stable_partition()</A></SAMP> if relative order is important.</P>
 <A NAME="sec5"><H3>Complexity</H3></A>
 <P>The <SAMP>partition()</SAMP> algorithm does at most <SAMP>(finish - start)/2 </SAMP>swaps, and applies the predicate exactly <SAMP>finish - start </SAMP>times. </P>
 <A NAME="sec6"><H3>Example</H3></A>

 <UL><PRE>//
 //  prtition.cpp
 //

 #include &lt;algorithm&gt;    // for copy
 #include &lt;deque&gt;        // for deque
 #include &lt;functional&gt;   // for unary_function
 #include &lt;iostream&gt;     // for cout, endl
 #include &lt;iterator&gt;     // for ostream_iterator


 // Create a new predicate from unary_function.
 template &lt;class Arg&gt;
 struct is_even : public std::unary_function&lt;Arg, bool&gt;
 {
     bool operator()(const Arg &amp;arg1) const {
         return (arg1 % 2) == 0;
     }
 };

 int main ()
 {
     typedef std::deque&lt;int, std::allocator&lt;int&gt; &gt; Deque;
     typedef std::ostream_iterator&lt;int, char,
                                   std::char_traits&lt;char&gt; &gt;
             Iter;

     // Initialize a deque with an array of integers.
     const Deque::value_type a[] = { 1, 2, 3, 4, 5,
                                     6, 7, 8, 9, 10 };

     Deque d1 (a + 0, a + sizeof a / sizeof *a);
     Deque d2 (d1);

     // Print out the original values.
     std::cout &lt;&lt; "Unpartitioned values: \t\t";
     std::copy (d1.begin (), d1.end (), Iter (std::cout, " "));

     // A partition of the deque according to even/oddness.
     std::partition (d2.begin (), d2.end (), is_even&lt;int&gt;());

     // Output result of partition.
     std::cout &lt;&lt; "\nPartitioned values: \t\t";
     std::copy (d2.begin (), d2.end (), Iter (std::cout, " "));

     // A stable partition of the deque according to
     // even/oddness.
     std::stable_partition (d1.begin (), d1.end (),
                            is_even&lt;int&gt;());

     // Output result of partition.
     std::cout &lt;&lt; "\nStable partitioned values: \t";
     std::copy (d1.begin (), d1.end (), Iter (std::cout, " "));
     std::cout &lt;&lt; std::endl;

     return 0;
 }


 Program Output:
 </PRE></UL>
 <UL><PRE>Unpartitioned values:     1 2 3 4 5 6 7 8 9 10
 Partitioned values:     10 2 8 4 6 5 7 3 9 1
 Stable partitioned values:   2 4 6 8 10 1 3 5 7 9
 </PRE></UL>
 <A NAME="sec7"><H3>See Also</H3></A>
 <P><SAMP><A HREF="stable-partition.html">stable_partition()</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 25.2.12</I></P>

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	<H2>partition()</H2>
	<P><B>Library:</B>  <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 places all of the entities that satisfy the given predicate before all of the entities that do not</P>
	<A NAME="sec3"><H3>Synopsis</H3></A>

	<PRE>#include <algorithm>

	namespace std {
	template <class BidirectionalIterator, class Predicate>
	BidirectionalIterator
	partition(BidirectionalIterator start,
	BidirectionalIterator finish,
	Predicate pred);
	}
	</PRE>
	<A NAME="sec4"><H3>Description</H3></A>
	<P>For the range <SAMP>[start, finish)</SAMP>, the <SAMP>partition()</SAMP> algorithm places all elements that satisfy the predicate <SAMP>pred</SAMP> before all elements that do not satisfy <SAMP>pred</SAMP>. It returns an iterator that is one past the end of the group of elements that satisfy <SAMP>pred</SAMP>. In other words, <SAMP>partition()</SAMP> returns <SAMP>i</SAMP> such that for any iterator <SAMP>j</SAMP> in the range <SAMP>[start, i)</SAMP>, <SAMP>pred(j) == true</SAMP>, and, for any iterator <SAMP>k</SAMP> in the range <SAMP>[i, finish)</SAMP>, <SAMP>pred(j) == false</SAMP>.</P>
	<P>Note that <SAMP>partition()</SAMP> does not necessarily maintain the relative order of the elements that match and elements that do not match the predicate. Use the algorithm <SAMP><A HREF="stable-partition.html">stable_partition()</A></SAMP> if relative order is important.</P>
	<A NAME="sec5"><H3>Complexity</H3></A>
	<P>The <SAMP>partition()</SAMP> algorithm does at most <SAMP>(finish - start)/2 </SAMP>swaps, and applies the predicate exactly <SAMP>finish - start </SAMP>times. </P>
	<A NAME="sec6"><H3>Example</H3></A>

	<UL><PRE>//
	// prtition.cpp
	//

	#include <algorithm> // for copy
	#include <deque> // for deque
	#include <functional> // for unary_function
	#include <iostream> // for cout, endl
	#include <iterator> // for ostream_iterator



	// Create a new predicate from unary_function.
	template <class Arg>
	struct is_even : public std::unary_function<Arg, bool>
	{
	bool operator()(const Arg &arg1) const {
	return (arg1 % 2) == 0;
	}
	};

	int main ()
	{
	typedef std::deque<int, std::allocator<int> > Deque;
	typedef std::ostream_iterator<int, char,
	std::char_traits<char> >
	Iter;

	// Initialize a deque with an array of integers.
	const Deque::value_type a[] = { 1, 2, 3, 4, 5,
	6, 7, 8, 9, 10 };

	Deque d1 (a + 0, a + sizeof a / sizeof *a);
	Deque d2 (d1);

	// Print out the original values.
	std::cout << "Unpartitioned values: \t\t";
	std::copy (d1.begin (), d1.end (), Iter (std::cout, " "));

	// A partition of the deque according to even/oddness.
	std::partition (d2.begin (), d2.end (), is_even<int>());

	// Output result of partition.
	std::cout << "\nPartitioned values: \t\t";
	std::copy (d2.begin (), d2.end (), Iter (std::cout, " "));

	// A stable partition of the deque according to
	// even/oddness.
	std::stable_partition (d1.begin (), d1.end (),
	is_even<int>());

	// Output result of partition.
	std::cout << "\nStable partitioned values: \t";
	std::copy (d1.begin (), d1.end (), Iter (std::cout, " "));
	std::cout << std::endl;

	return 0;
	}


	Program Output:
	</PRE></UL>
	<UL><PRE>Unpartitioned values: 1 2 3 4 5 6 7 8 9 10
	Partitioned values: 10 2 8 4 6 5 7 3 9 1
	Stable partitioned values: 2 4 6 8 10 1 3 5 7 9
	</PRE></UL>
	<A NAME="sec7"><H3>See Also</H3></A>
	<P><SAMP><A HREF="stable-partition.html">stable_partition()</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 25.2.12</I></P>

	<BR>
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