stl newbie, set intersection of two sets into another set

[Yves M]

It's pretty simple, I'd like to put the intersection of two sets into another set. The problem I have is with the output iterator. I don't know how to define one for std::set :/

Here is my code up to now :

#include <set>
#include <map>
#include <algorithm>

using namespace std;

int main()
{
  set<long> Source, Target, Intersection		

  Source.insert(10);
  Source.insert(20);
  Target.insert(5);
  Target.insert(10);
  set_intersection(Source.begin(), Source.end(), Target.begin(), Target.end(), ???);
  return 0;
}

Unfortunately the examples I found on my standard reference site all use the algorithms for C style arrays and the output iterator is always an ostream :/

[Yves M]

Ok, I got it

#include <set>
#include <map>
#include <algorithm>

using namespace std;

int main()
{
  set<long> Source, Target, Intersection	
  insert_iterator<set<long> > ii(Intersection, Intersection.begin());	

  Source.insert(10);
  Source.insert(20);
  Target.insert(5);
  Target.insert(10);
  set_intersection(Source.begin(), Source.end(), Target.begin(), Target.end(), ii);
  return 0;
}

[jwbarton]

Or without the extra variable:

set_intersection( Source.begin(), Source.end(), Target.begin(), Target.end(), inserter(Intersection,Intersection.begin()) );

Best regards,
John

[Yves M]

Interesting, thanks