c++ stl 已排序区间算法 两个已排序集合的差集set_difference、set_symmetric_difference使用方法

template<typename T>
inline void PRINT_ELEMENTS(const T & coll, const string& optcstr = "")
{
	cout << optcstr;
	for (auto elem : coll)
	{
		cout << elem << ' ';
	}
	cout << endl;
}
int main()
{
	vector<int>a{ 1,2,2,4,6,7,7,9 };
	deque<int>b{ 2,2,2,3,6,6,8,9 };
	PRINT_ELEMENTS(a, "a: ");
	PRINT_ELEMENTS(b, "b: ");

	cout << "set_difference: ";
	set_difference(a.cbegin(), a.cend(), b.cbegin(), b.cend(), ostream_iterator<int>(cout, " "));
	cout << endl;

	cout << "set_symmetric_difference: ";
	set_symmetric_difference(a.cbegin(), a.cend(), b.cbegin(), b.cend(), ostream_iterator<int>(cout, " "));
	cout << endl;

}