宁夏建设厅网站首页衡水seo营销

C++之unordered_set和unordered_map的模拟实现

前言：
前面篇章学习了C++对unordered_set和unordered_map的认识和应用，接下来继续学习，C++的unordered_set和unordered_map模拟实现等知识。
/知识点汇总/

1、unordered_set的模拟实现

#define _CRT_SECURE_NO_WARNINGS 1#include "HashBucket.h"namespace bit1
{template<class K, class Hash = HashFunc<K>>//class Hash = HashFunc<K>修改参数在这里传入class unordered_set{struct SetKeyOfT{const K& operator()(const K& key){return key;}};public://迭代器typedef typename HashTable<K,const K, SetKeyOfT, Hash>::Iterator iterator;typedef typename HashTable<K, const K, SetKeyOfT, Hash>::const_Iterator const_iterator;iterator begin(){return _ht.Begin();}iterator end(){return _ht.End();}const_iterator begin() const{return _ht.Begin();}const_iterator end() const{return _ht.End();//这里报错，是因为End()中的返回值，this指针问题}pair<iterator, bool> insert(const K& key){return _ht.Insert(key);}iterator find(const K& key){return _ht.Find(key);}bool erase(const K& key){return _ht.Erase(key);}private://HashTable<K, V> _ht;HashTable<K,const K, SetKeyOfT, Hash> _ht;//+const};void test_unordered_set(){unordered_set<int> s;s.insert(31);s.insert(11);s.insert(5);s.insert(15);s.insert(25);unordered_set<int>::iterator it = s.begin();while (it != s.end()){//*it += 1;//set是不能被修改的，需要const修饰cout << *it << " ";++it;}cout << endl;for (auto e : s){cout << e << " ";}cout << endl;}//const迭代器void Func(const unordered_set<int>& s){unordered_set<int>::iterator it = s.begin();while (it != s.end()){//*it = 1;cout << *it << " ";++it;}cout << endl;}
}

2、unordered_map的模拟实现

#define _CRT_SECURE_NO_WARNINGS 1#include "HashBucket.h"namespace bit1
{template<class K, class V,class Hash = HashFunc<K>>class unordered_map{struct MapKeyOfT{const K& operator()(const pair<K, V>& kv){return kv.first;}};public:typedef typename HashTable<K, pair<const K, V>, MapKeyOfT, Hash>::Iterator iterator;iterator begin(){return _ht.Begin();}iterator end(){return _ht.End();}V& operator[](const K& key){pair<iterator, bool> ret = insert(make_pair(key, V()));return ret.first->second;//报错发现->还没有写}// 21:15pair<iterator, bool> insert(const pair<K, V>& kv){return _ht.Insert(kv);}private:HashTable<K, pair<const K, V>, MapKeyOfT, Hash> _ht;};void test_unordered_map(){string arr[] = { "苹果", "西瓜", "苹果", "西瓜", "苹果", "苹果", "西瓜","苹果", "香蕉", "苹果", "香蕉","苹果","草莓", "苹果","草莓" };unordered_map<string, int> countMap;for (auto& e : arr){countMap[e]++;}unordered_map<string, int>::iterator it = countMap.begin();while (it != countMap.end()){//it->first += 'x'; // key不能修改it->second += 1;  // value可以修改cout << it->first << ":" << it->second << endl;++it;}cout << endl;for (auto& kv : countMap){cout << kv.first << ":" << kv.second << endl;}cout << endl;}
}