C++17之for循环新能力

map<string, int> map;
map["Apple"] = 10;

/* key为string类型，value为int类型 */for (auto [key, value] : map) {
    cout << key << " " << value << endl;
}

输出: Apple 10

list<pair<int, double>> list;
list.push_back(make_pair(1, 9.9));

/* key为int类型，value为double类型 */for (auto [key, value] : list) {
    cout << key << value << endl;
}

输出: 19.9