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                       Standard C++ Library
             Copyright 1998, Rogue Wave Software, Inc.


NAME
     inplace_merge

      - Merges two sorted sequences into one.



SYNOPSIS
     #include <algorithm>
     template <class BidirectionalIterator>
      void inplace_merge(BidirectionalIterator first,
                         BidirectionalIterator middle,
                         BidirectionalIterator last);

     template <class BidirectionalIterator, class Compare>
      void inplace_merge(BidirectionalIterator first,
                         BidirectionalIterator middle,
                         BidirectionalIterator last,
                         Compare comp);



DESCRIPTION
     The inplace_merge algorithm merges  two  sorted  consecutive
     ranges  [first,  middle)  and  [middle,  last), and puts the
     result of the merge into the range [first, last). 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.

     There are two versions of the inplace_merge  algorithm.  The
     first version uses the less than operator (operator<) as the
     default for comparison, and the  second  version  accepts  a
     third argument that specifies a comparison operator.



COMPLEXITY
     When enough additional memory  is  available,  inplace_merge
     does  at  most  (last  - first) - 1 comparisons. If no addi-
     tional memory is available, an algorithm with O(NlogN)  com-
     plexity (where N is equal to last-first) may be used.



EXAMPLE
     //
     // merge.cpp
     //
      #include <algorithm>
      #include <vector>
      #include <functional>
      #include <iostream>
     using namespace std;

     int main()
      {
       int d1[4] = {1,2,3,4};
       int d2[8] = {11,13,15,17,12,14,16,18};

        // Set up two vectors
       vector<int> v1(d1,d1 + 4), v2(d1,d1 + 4);


        // Set up four destination vectors
       vector<int> v3(d2,d2 + 8),v4(d2,d2 + 8),
                   v5(d2,d2 + 8),v6(d2,d2 + 8);
        // Set up one empty vector
       vector<int> v7;
        // Merge v1 with v2
       merge(v1.begin(),v1.end(),v2.begin(),v2.end(),
             v3.begin());
        // Now use comparator
       merge(v1.begin(),v1.end(),v2.begin(),v2.end(),v4.begin(),
             less<int>());
        // In place merge v5
       vector<int>::iterator mid = v5.begin();
       advance(mid,4);
        inplace_merge(v5.begin(),mid,v5.end());
        // Now use a comparator on v6
       mid = v6.begin();
       advance(mid,4);
        inplace_merge(v6.begin(),mid,v6.end(),less<int>());
        // Merge v1 and v2 to empty vector using insert iterator
       merge(v1.begin(),v1.end(),v2.begin(),v2.end(),
             back_inserter(v7));
        // Copy all cout
       ostream_iterator<int,char> out(cout," ");
       copy(v1.begin(),v1.end(),out);
       cout << endl;
       copy(v2.begin(),v2.end(),out);
       cout << endl;
       copy(v3.begin(),v3.end(),out);
       cout << endl;
       copy(v4.begin(),v4.end(),out);
       cout << endl;
       copy(v5.begin(),v5.end(),out);
       cout << endl;
       copy(v6.begin(),v6.end(),out);
       cout << endl;
       copy(v7.begin(),v7.end(),out);
       cout << endl;

        // Merge v1 and v2 to cout
       merge(v1.begin(),v1.end(),v2.begin(),v2.end(),
             ostream_iterator<int,char>(cout," "));
       cout << endl;
       return 0;
      }


     Program Output



     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



WARNINGS
     If your compiler does not support default  template  parame-
     ters,  then you always need to supply the Allocator template
     argument. For instance, you have to write:

     vector<int, allocator,int> >

     instead of:

     vector<int>

     If your compiler does not support namespaces,  then  you  do
     not need the using declaration for std.



SEE ALSO
     merge

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