Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.

NAME

  set_intersection  - Basic set operation for sorted sequences.

SYNOPSIS

  #include <algorithm>

  template <class InputIterator1, class InputIterator2,
           class OutputIterator>
  OutputIterator
  set_intersection (InputIterator1 first1, InputIterator1 last1,
                   InputIterator2 first2, InputIterator last2,
                   OutputIterator result);

  template <class InputIterator1, class InputIterator2,
           class OutputIterator, class Compare>
  OutputIterator
  set_intersection (InputIterator1 first1, InputIterator1 last1,
                   InputIterator2 first2, InputIterator2 last2,
                   OutputIterator result, Compare comp);

DESCRIPTION

  The set_intersection algorithm constructs a sorted intersection of elements
  from the two ranges.  It returns the end of the constructed range.  When it
  finds an element present in both ranges, set_intersection always copies the
  element from the first range into result.  This means that the result of
  set_intersection is guaranteed to be stable.   The result of
  set_intersection is undefined if the result range overlaps with either of
  the original ranges.

  set_intersection assumes that the ranges are sorted using the default
  comparison operator less than (<), unless an alternative comparison
  operator (comp) is provided.

COMPLEXITY

  At most ((last1 - first1) + (last2 - first2)) * 2 -1  comparisons are
  performed.

EXAMPLE

  //
  // set_intr.cpp
  //
   #include <algorithm>
   #include <set>
   #include <iostream.h>
  int main()
   {

     //Initialize some sets
    int a1[10] = {1,3,5,7,9,11};
    int a3[4]  = {3,5,7,8};
    set<int, less<int> > odd(a1, a1+6),
                         result, small(a3,a3+4);

     //Create an insert_iterator for result
    insert_iterator<set<int, less<int> > >
                  res_ins(result, result.begin());

     //Demonstrate set_intersection
    cout << "The result of:" << endl << "{";
    copy(small.begin(),small.end(),
         ostream_iterator<int,char>(cout," "));
    cout << "} intersection {";
    copy(odd.begin(),odd.end(),
         ostream_iterator<int,char>(cout," "));
    cout << "} =" << endl << "{";
     set_intersection(small.begin(), small.end(),
                    odd.begin(), odd.end(), res_ins);
    copy(result.begin(),result.end(),
         ostream_iterator<int,char>(cout," "));
    cout << "}" << endl << endl;

    return 0;
   }

  Output :
  The result of:
  {3 5 7 8 } intersection {1 3 5 7 9 11 } =
  {3 5 7 }

WARNING

  If your compiler does not support default template parameters, then you
  need to always supply the Compare template argument and the Allocator
  template argument. For instance, you will need to write :

  set<int, less<int> allocator<int> >

  instead of :

  set<int>

SEE ALSO

  includes, set, set_union, set_difference, set_symmetric_difference

STANDARDS CONFORMANCE

  ANSI X3J16/ISO WG21 Joint C++ Committee



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