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


NAME
     unique, unique_copy

      - Removes consecutive duplicates from a range of values and
     places the resulting unique values into the result.



SYNOPSIS
     #include <algorithm>
     template <class ForwardIterator>
      ForwardIterator
         unique (ForwardIterator first, ForwardIterator last);
     template <class ForwardIterator, class BinaryPredicate>
      ForwardIterator
         unique (ForwardIterator first, ForwardIterator last,
                BinaryPredicate binary_pred);
     template <class InputIterator, class OutputIterator>
      OutputIterator
         unique_copy (InputIterator first, InputIterator last,
                     OutputIterator result);
     template <class InputIterator, class OutputIterator,
              class BinaryPredicate>
      OutputIterator
         unique_copy (InputIterator first, InputIterator last,
                     OutputIterator result,
                     BinaryPredicate binary_pred);



DESCRIPTION
     The unique algorithm moves through a sequence and eliminates
     all  but  the  first element from every consecutive group of
     equal elements. There are two versions of the  algorithm-one
     that  tests  for  equality  and a second that tests adjacent
     elements against a binary predicate. An element is unique if
     it does not meet the corresponding condition listed here:

     *i  ==  *(i  -  1)

     or

     binary_pred(*i, *(i - 1)) == true.

     If an element is unique, it is copied to the  front  of  the
     sequence, overwriting the existing elements. Once all unique
     elements have been identified. The remainder of the sequence
     is left unchanged, and unique returns the end of the result-
     ing range.

     The unique_copy algorithm  copies  the  first  element  from
     every consecutive group of equal elements to an OutputItera-
     tor. The unique_copy algorithm  also  has  two  versions-one
     that  tests  for  equality  and a second that tests adjacent
     elements against a binary predicate.

     unique_copy returns the end of the resulting range.



COMPLEXITY
     For unique_copy, it is exactly (last - first) -  1  applica-
     tions of the corresponding predicate are performed.



EXAMPLE
     //
     // unique.cpp
     //
     #include <algorithm>
     #include <vector>
     #include <iostream>
     using namespace std;
     int main()
      {
     //Initialize two vectors
     int a1[20] = {4, 5, 5, 9, -1, -1, -1, 3, 7, 5,
                  5, 5, 6, 7, 7, 7, 4, 2, 1, 1};
     vector<int> v(a1+0, a1+20), result;

     //Create an insert_iterator for results
     insert_iterator<vector<int> > ins(result, result.begin());

     //Demonstrate includes
     cout << "The vector: " << endl << "    ";
     copy(v.begin(),v.end(),
         ostream_iterator<int,char>(cout," "));

     //Find the unique elements
     unique_copy(v.begin(), v.end(), ins);

     //Display the results
     cout << endl << endl
          << "Has the following unique elements:"
          << endl << "     ";

     copy(result.begin(),result.end(),
         ostream_iterator<int,char>(cout," "));
     return 0;
     }

     Program Output



     The vector:
     4 5 5 9 -1 -1 -1 3 7 5 5 5 6 7 7 7 4 2 1 1
     Has the following unique elements:
     4 5 9 -1 3 7 5 6 7 4 2 1



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

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