Algorithm
A basic set operation for constructing a sorted symmetric difference.
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>
using namespace std;
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+0,a1+6), result,
small(a3+0,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;
}
Program 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 always need to supply the Compare template argument and the Allocator template argument. For instance, you need to write:
set<int, less<int>, allocator<int> >
instead of:
set<int>
If your compiler does not support namespaces, then you do not need the using declaration for std.
includes, set, set_union,set_intersection, set_difference