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<H2>inplace_merge()</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 merges two sorted consecutive sequences into a single sorted sequence</P>
<A NAME="sec3"><H3>Synopsis</H3></A>

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

namespace std {
  template &lt;class BidirectionalIterator&gt;
  void inplace_merge(BidirectionalIterator start,
                     BidirectionalIterator mid,
                     BidirectionalIterator finish);

  template &lt;class BidirectionalIterator, class Compare&gt;
  void inplace_merge(BidirectionalIterator start,
                     BidirectionalIterator mid,
                     BidirectionalIterator finish, 
                     Compare comp);
}
</PRE>
<A NAME="sec4"><H3>Description</H3></A>
<P>The <SAMP>inplace_merge()</SAMP> algorithm merges two sorted consecutive ranges <SAMP>[start, mid)</SAMP> and <SAMP>[mid, finish)</SAMP>, and puts the result of the merge into the range <SAMP>[start, finish)</SAMP>. The merge is stable, which means that if the two ranges contain equivalent elements, the elements from the first range always precede the elements from the second. </P>
<P>There are two versions of the <SAMP>inplace_merge()</SAMP> algorithm. The first version uses <SAMP>operator&lt;()</SAMP> as the default for comparison, and the second version accepts a third argument that specifies a binary predicate function object.</P>
<A NAME="sec5"><H3>Complexity</H3></A>
<P>When enough additional memory is available, <SAMP>inplace_merge()</SAMP> does at most<SAMP> (finish - start) - 1</SAMP> comparisons. If no additional memory is available, an algorithm with <SAMP>O(N * log(N))</SAMP> complexity may be used, where <SAMP>N</SAMP> is equal to <SAMP>finish - start</SAMP>.</P>
<A NAME="sec6"><H3>Example</H3></A>

<UL><PRE>//
//  merge.cpp
//

#include &lt;algorithm&gt;    // advance, copy, inplace_merge, merge
#include &lt;functional&gt;   // less
#include &lt;iostream&gt;     // cout
#include &lt;iterator&gt;     // back_inserter, ostream_iterator
#include &lt;vector&gt;       // vector


int main ()
{
    typedef std::vector&lt;int, std::allocator&lt;int&gt; &gt; Vector;

    const Vector::value_type d1[] = { 1, 2, 3, 4};
    const Vector::value_type d2[] = { 11, 13, 15, 17, 
                                      12, 14, 16, 18};

    // Set up two vectors.
    Vector v1 (d1 + 0, d1 + sizeof d1 / sizeof *d1);
    Vector v2 (d1 + 0, d1 + sizeof d1 / sizeof *d1);

    // Set up four destination vectors.
    Vector v3 (d2 + 0, d2 + sizeof d2 / sizeof *d2);
    Vector v4 (v3);
    Vector v5 (v3);
    Vector v6 (v3);

    // Set up one empty vector.
    Vector v7;

    // Merge v1 with v2.
    std::merge (v1.begin (), v1.end (),
                v2.begin (), v2.end (), v3.begin ());

    // Now use comparator.
    std::merge (v1.begin (), v1.end (),
                v2.begin (), v2.end (), v4.begin (), 
                std::less&lt;int&gt;());

    // In place merge v5.
    Vector::iterator mid = v5.begin ();
    std::advance (mid, 4);   // equivalent to mid += 4 
                             // but more generic
    std::inplace_merge (v5.begin (), mid, v5.end ());

    // Now use a comparator on v6.
    mid = v6.begin ();
    std::advance (mid, 4);   // equivalent to mid += 4 
                             // but more generic
    std::inplace_merge (v6.begin (), mid, v6.end (), 
                        std::less&lt;int&gt;());    

    // Merge v1 and v2 to empty vector using insert iterator.
    std::merge (v1.begin (), v1.end (),
                v2.begin (), v2.end (), 
                std::back_inserter (v7));

    // Copy all to cout.
    std::ostream_iterator&lt;int, char, std::char_traits&lt;char&gt; &gt;
        out (std::cout," ");

    std::copy (v1.begin (), v1.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v2.begin(), v2.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v3.begin (), v3.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v4.begin (), v4.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v5.begin (), v5.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v6.begin (),v6.end (), out);
    std::cout &lt;&lt; std::endl;
    std::copy (v7.begin (), v7.end (), out);
    std::cout &lt;&lt; std::endl;

    // Merge v1 and v2 to cout.
    std::merge (v1.begin (), v1.end (), 
                v2.begin (), v2.end (), out);

    return 0;
}


Program Output:
</PRE></UL>
<UL><PRE>1 2 3 4 
1 2 3 4 
1 1 2 2 3 3 4 4 
1 1 2 2 3 3 4 4 
11 12 13 14 15 16 17 18 
11 12 13 14 15 16 17 18 
1 1 2 2 3 3 4 4 
1 1 2 2 3 3 4 4 
</PRE></UL>
<A NAME="sec7"><H3>See Also</H3></A>
<P><SAMP><A HREF="merge.html">merge()</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 25.3.4</I></P>

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