unordered_map/unordered_set & unordered_multimap/unordered_multiset非关联容器

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unordered_map & unordered_multimap

#include<iostream> #include<unordered_map> #include<string> #include<iterator> using namespace std; int main() {         pair<int,string> arr[5]={                 pair<int,string>(1,"北京"),                 pair<int,string>(2,"上海"),                 pair<int,string>(2,"昆明"),                 pair<int,string>(4,"重庆"),                 pair<int,string>(3,"天津")         };         unordered_map<int ,string> test1(arr,arr+5);         unordered_map<int ,string>::iterator it = test1.begin();         for(;it!=test1.end();++it)         {                 cout<<it->first<<" "<<it->second<<endl;         }         //无序map,不能使用less<>和greater<>来排序了         cout<<"test unordered_multimap:"<<endl;         unordered_multimap<int ,string> test2(arr,arr+5);         for(auto& elem:test2)         {                 cout<<elem.first<<" "<<elem.second<<endl;         }         cout<<"test random access:"<<endl;         cout<<test1[1]<<endl;  // unordered_multimap不支持随机访问         unordered_multimap<int,string>::iterator umit = test2.find(2);         cout<<umit->first<<" "<<umit->second<<endl; }

unordered_set & unordered_multiset

#include<iostream> #include<unordered_set> using namespace std; int main() {         int arr[7] = {2,2,1,3,4,5,3};         unordered_set<int> test1(arr,arr+7);         for(auto& elem:test1)                 cout<<elem<<" ";         cout<<endl;         cout<<"test unordered_multiset"<<endl;         unordered_multiset<int> test2(arr,arr+7);         for(auto& elem:test2)                 cout<<elem<<" ";         cout<<endl;         unordered_multiset<int> test3(arr,arr+7);         cout<<"test random access"<<endl;         cout<<*(test2.find(3))<<endl;         cout<<*(test2.find(2))<<endl;         cout<<"value = 2 cnt:"<<test2.count(2)<<endl;         return 0; }