stl - Compare two vectors C++

Question

I was wondering is there any function to compare 2 string vectors to return the number of different(or the same) elements? Or i have to iterate over both of them and test item by item.
Thanks.

Answer 1

std::sort(v1.begin(), v1.end());
std::sort(v2.begin(), v2.end());
std::vector<string> v3;
std::set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), std::back_inserter(v3));

Or, if you don't want to sort:

std::set<string> s1(v1.begin(), v1.end());
std::set<string> s2(v2.begin(), v2.end());
std::vector<string> v3;
std::set_intersection(s1.begin(), s1.end(), s2.begin(), s2.end(), std::back_inserter(v3));

You may want to use a multiset if there could be duplicates in a vector.