set_symmetric_difference

Algorithm

• Summary
• Data Type and Member Function Indexes
• Synopsis
• Description
• Complexity
• Example
• Warning
• See Also

Basic set operation for sorted sequences.

None

#include <algorithm>

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

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

set_symmetric_difference constructs a sorted symmetric difference of the elements from the two ranges. This means that the constructed range includes copies of the elements that are present in the range [first1, last1) but not present in the range [first2, last2)and copies of the elements that are present in the range [first2, last2) but not in the range [first1, last1). It returns the end of the constructed range.

For example, suppose we have two sets:

1 2 3 4 5

and

3 4 5 6 7

The set_symmetric_difference of these two sets is:

1 2 6 7

The result of set_symmetric_difference is undefined if the result range overlaps with either of the original ranges.

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

Use the set_symmetric_difference algorithm to return a result that includes elements that are present in the first set and not in the second.

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

//
// set_s_di.cpp
//
 #include<algorithm>
 #include<set>
 #include <istream.h>

 int main()
 {

   //Initialize some sets
   int a1[] = {1,3,5,7,9,11};
   int a3[] = {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_symmetric_difference
   cout << "The symmetric difference of:" << endl << "{";
   copy(small.begin(),small.end(),
        ostream_iterator<int,char>(cout," "));
   cout << "} with {";
   copy(odd.begin(),odd.end(),
        ostream_iterator<int,char>(cout," "));
   cout << "} =" << endl << "{";
   set_symmetric_difference(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 symmetric difference of:
{3 5 7 8 } with {1 3 5 7 9 11 } =
{1 8 9 11 }

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>

includes, set, set_union, set_intersection, set_difference

©Copyright 1996, Rogue Wave Software, Inc.