📌 사용 예시

for (auto iter = v.begin(); iter != v.end(); iter++)
		cout << *iter << " ";
	cout << endl;

vector<int>::iterator iter;
	for ( iter = v.begin(); iter != v.end(); iter++)
		cout << *iter << " ";
	cout << endl;

vector<int>::reverse_iterator riter;
	for (riter = v.rbegin(); riter != v.rend(); ++riter)
		cout << *riter << " ";
	cout << endl;