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<Head>
<Title>partial_sort_copy</Title>
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<H1>partial_sort_copy</H1>
<Table CellPadding=0 CellSpacing=0 width=100%>
<TR>
<TD Align=left><Img src = "algorithms.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD>
<TD Align=right><Img src = "function.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD>
</TR>
<TR>
<TD Align=left VAlign=top><b>Category</b>: algorithms</TD>
<TD Align=right VAlign=top><b>Component type</b>: function</TD>
</TR>
</Table>
<h3>Prototype</h3>
<tt>Partial_sort_copy</tt> is an overloaded name; there are actually two <tt>partial_sort_copy</tt>
functions.
<pre>
template <class <A href="InputIterator.html">InputIterator</A>, class <A href="RandomAccessIterator.html">RandomAccessIterator</A>>
RandomAccessIterator
partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last);
template <class <A href="InputIterator.html">InputIterator</A>, class <A href="RandomAccessIterator.html">RandomAccessIterator</A>,
class <A href="StrictWeakOrdering.html">StrictWeakOrdering</A>>
RandomAccessIterator
partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last, Compare comp);
</pre>
<h3>Description</h3>
<tt>Partial_sort_copy</tt> copies the smallest <tt>N</tt> elements from the range
<tt>[first, last)</tt> to the range <tt>[result_first, result_first + N)</tt>, where
<tt>N</tt> is the smaller of <tt>last - first</tt> and <tt>result_last - result_first</tt>.
The elements in <tt>[result_first, result_first + N)</tt> will be in ascending
order.
<P>
The two versions of <tt>partial_sort_copy</tt> differ in how they define whether one
element is less than another. The first version compares
objects using <tt>operator<</tt>, and the second compares objects using
a <A href="functors.html">function object</A> <tt>comp</tt>.
<P>
The postcondition for the first version of <tt>partial_sort_copy</tt> is as follows.
If <tt>i</tt> and <tt>j</tt> are
any two valid iterators in the range <tt>[result_first, result_first +
N)</tt> such that <tt>i</tt> precedes <tt>j</tt>, then <tt>*j < *i</tt> will be <tt>false</tt>.
The corresponding postcondition for the second version is that
<tt>comp(*j, *i)</tt> will be <tt>false</tt>.
<P>
The return value is <tt>result_first + N</tt>.
<h3>Definition</h3>
Defined in the standard header <A href="algorithm">algorithm</A>, and in the nonstandard
backward-compatibility header <A href="algo.h">algo.h</A>.
<h3>Requirements on types</h3>
For the first version:
<UL>
<LI>
<tt>InputIterator</tt> is a model of <A href="InputIterator.html">InputIterator</A>.
<LI>
<tt>RandomAccessIterator</tt> is a model of <A href="RandomAccessIterator.html">Random Access Iterator</A>.
<LI>
<tt>RandomAccessIterator</tt> is mutable.
<LI>
The value types of <tt>InputIterator</tt> and <tt>RandomAccessIterator</tt>
are the same.
<LI>
<tt>RandomAccessIterator</tt>'s value type is <A href="LessThanComparable.html">LessThan Comparable</A>.
<LI>
The ordering relation on <tt>RandomAccessIterator</tt>'s value type is
a <i>strict weak ordering</i>, as defined in the <A href="LessThanComparable.html">LessThan Comparable</A>
requirements.
</UL>
For the second version:
<UL>
<LI>
<tt>InputIterator</tt> is a model of <A href="InputIterator.html">InputIterator</A>.
<LI>
<tt>RandomAccessIterator</tt> is a model of <A href="RandomAccessIterator.html">Random Access Iterator</A>.
<LI>
<tt>RandomAccessIterator</tt> is mutable.
<LI>
The value types of <tt>InputIterator</tt> and <tt>RandomAccessIterator</tt>
are the same.
<LI>
<tt>StrictWeakOrdering</tt> is a model of <A href="StrictWeakOrdering.html">Strict Weak Ordering</A>.
<LI>
<tt>RandomAccessIterator</tt>'s value type is convertible to
<tt>StrictWeakOrdering</tt>'s argument type.
</UL>
<h3>Preconditions</h3>
<UL>
<LI>
<tt>[first, last)</tt> is a valid range.
<LI>
<tt>[result_first, result_last)</tt> is a valid range.
<LI>
<tt>[first, last)</tt> and <tt>[result_first, result_last)</tt> do not overlap.
</UL>
<h3>Complexity</h3>
Approximately <tt>(last - first) * log(N)</tt> comparisons, where <tt>N</tt> is the
smaller of <tt>last - first</tt> and <tt>result_last - result_first</tt>.
<h3>Example</h3>
<pre>
int A[] = {7, 2, 6, 11, 9, 3, 12, 10, 8, 4, 1, 5};
const int N = sizeof(A) / sizeof(int);
vector<int> V(4);
partial_sort_copy(A, A + N, V.begin(), V.end());
copy(V.begin(), V.end(), ostream_iterator<int>(cout, " "));
// The printed result is "1 2 3 4".
</pre>
<h3>Notes</h3>
<h3>See also</h3>
<tt><A href="partial_sort.html">partial_sort</A></tt>,
<tt><A href="sort.html">sort</A></tt>,
<tt><A href="stable_sort.html">stable_sort</A></tt>,
<tt><A href="binary_search.html">binary_search</A></tt>,
<tt><A href="lower_bound.html">lower_bound</A></tt>,
<tt><A href="upper_bound.html">upper_bound</A></tt>,
<tt><A href="less.html">less</A><T></tt>,
<A href="StrictWeakOrdering.html">StrictWeakOrdering</A>,
<A href="LessThanComparable.html">LessThan Comparable</A>
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