# 25 Algorithms library [algorithms]

## 25.4 Sorting and related operations [alg.sorting]

### 25.4.5 Set operations on sorted structures [alg.set.operations]

#### 25.4.5.5set_symmetric_difference[set.symmetric.difference]

``` 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); ```

Effects: Copies the elements of the range [first1,last1) that are not present in the range [first2,last2), and the elements of the range [first2,last2) that are not present in the range [first1,last1) 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, then |m - n| of those elements shall be copied to the output range: the last m - n of these elements from [first1,last1) if m > n, and the last n - m of these elements from [first2,last2) if m < n.