2021-4-1 C++ STL之unordered_map

unordered_map

unordered_map底层实现是哈希表，所以不会根据key来排序

undered_map<T1,T2> m;		//T1是key值，T2是value值，初始的时候 m 是空映射

插入方式：键值对的形式插入

 unordered_map<int, int> map;
        for (int i=0; i<list.size(); i++){
            map[i] = list[i];
        }
        cout << map[0] << endl;
        for (unordered_map<int, int>::iterator i = map.begin(); i != map.end(); i++){
            cout << i->first << ‘ ‘ << i->second << endl;
        }
        if (map.find(3) != map.end()) {
            cout << "find key=" << map.find(3)->first << ", value=" << map.find(3)->second << endl;
        }
        if (map.count(5) > 0) {
            cout << "find 5: " << map.count(5) << endl;
        }