set_symmetric_difference

     Algorithm

Summary

Basic set operation for sorted sequences.

Synopsis

Synopsis

#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);

Description

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 comparision 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.

Complexity

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

Example

//
// 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>(cout," "));
   cout << "} with {";
   copy(odd.begin(),odd.end(),
        ostream_iterator<int>(cout," "));
   cout << "} =" << endl << "{";
   set_symmetric_difference(small.begin(), small.end(),
                       odd.begin(), odd.end(), res_ins);
   copy(result.begin(),result.end(),
        ostream_iterator<int>(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 }

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>

instead of :

set<int>