Computes symmetric difference of two sorted ranges: the elements that are found in either of the ranges, but not in both of them are copied to the range beginning atd_first. The output range is also sorted.

If[first1, last1) containsm elements that are equivalent to each other and[first2, last2) containsn elements that are equivalent to them, thenstd::abs(m- n) of those elements will be copied to the output range, preserving order:

• ifm> n, the finalm- n of these elements from[first1, last1).
• ifm< n, the finaln- m of these elements from[first2, last2).

If the output range overlaps with[first1, last1) or[first2, last2), the behavior is undefined.

[edit]Parameters

[edit]Return value

Iterator past the end of the constructed range.

[edit]Complexity

Given\(\scriptsize N_1\)N1 asstd::distance(first1, last1) and\(\scriptsize N_2\)N2 asstd::distance(first2, last2):

[edit]Exceptions

The overloads with a template parameter namedExecutionPolicy report errors as follows:

• If execution of a function invoked as part of the algorithm throws an exception andExecutionPolicy is one of thestandard policies,std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory,std::bad_alloc is thrown.

[edit]Possible implementation

template<class InputIt1,class InputIt2,class OutputIt>OutputIt set_symmetric_difference(InputIt1 first1, InputIt1 last1,                                  InputIt2 first2, InputIt2 last2, OutputIt d_first){while(first1!= last1){if(first2== last2)returnstd::copy(first1, last1, d_first); if(*first1<*first2)*d_first++=*first1++;else{if(*first2<*first1)*d_first++=*first2;else++first1;++first2;}}returnstd::copy(first2, last2, d_first);}

template<class InputIt1,class InputIt2,class OutputIt,class Compare>OutputIt set_symmetric_difference(InputIt1 first1, InputIt1 last1,                                  InputIt2 first2, InputIt2 last2,                                  OutputIt d_first, Compare comp){while(first1!= last1){if(first2== last2)returnstd::copy(first1, last1, d_first); if(comp(*first1,*first2))*d_first++=*first1++;else{if(comp(*first2,*first1))*d_first++=*first2;else++first1;++first2;}}returnstd::copy(first2, last2, d_first);}

[edit]Example

#include <algorithm>#include <iostream>#include <iterator>#include <vector> int main(){std::vector<int> v1{1,2,3,4,5,6,7,8};std::vector<int> v2{5,7,9,10};std::sort(v1.begin(), v1.end());std::sort(v2.begin(), v2.end()); std::vector<int> v_symDifference;     std::set_symmetric_difference(v1.begin(), v1.end(), v2.begin(), v2.end(),std::back_inserter(v_symDifference)); for(int n: v_symDifference)std::cout<< n<<' ';std::cout<<'\n';}

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[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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