#include <algorithm>
  iterator set_intersection( iterator start1, iterator end1, iterator start2, iterator end2, iterator result );
  iterator set_intersection( iterator start1, iterator end1, iterator start2, iterator end2, iterator result, StrictWeakOrdering cmp );

The set_intersection() algorithm computes the intersection of the two sets defined by [start1,end1) and [start2,end2) and stores the intersection starting at result.

Both of the sets, given as ranges, must be sorted in ascending order.

The return value of set_intersection() is an iterator to the end of the intersection range.

If the strict weak ordering comparison function object cmp is not specified, set_intersection() will use the < operator to compare elements.