template<class InputIterator1, class InputIterator2,
class OutputIterator>
OutputIterator
set_difference(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result);
template<class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator
set_difference(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result, Compare comp);
Effects: Copies the elements of the range [first1,last1) which are not present in the range [first2,last2) to the range beginning at result. The elements in the constructed range are sorted.
Requires: The resulting range shall not overlap with either of the original ranges.
Returns: The end of the constructed range.
Complexity: At most 2 * ((last1 - first1) + (last2 - first2)) - 1 comparisons.
Remarks: If [first1,last1) contains m elements that are equivalent to each other and [first2,last2) contains n elements that are equivalent to them, the last max(m - n, 0) elements from [first1,last1) shall be copied to the output range.