I decide to write to my blogs in English. When I meet something hard to depict, I'll add some Chinese necessarily.

The differences between these containers are :

1. The keys of set and map are unique, but they could be multiple for multiset and multimap.
2. Unordered_set and unordered_map are implemented by hash map, but the above 4 containers are implemented by Red-Black tree. They could have been named as hash_map, however, these names seem to have be  used by other standards. So this ugly name ‘unordered’ is adopted in contrast to the attribute 'ordered' of the above 4 containers.

#include<map>

#include<stdio.h>

#include<unordered_map>

#include<algorithm>

//#include<unordered_multimap>  //there isn't such a library

#include<string>

#include<iostream>

using namespace std;

int main()

{

	unordered_multimap<int, string> mapStudent1;

	mapStudent1.insert(pair<int, string>(1, "student_one"));

	mapStudent1.insert(pair<int, string>(2, "student_two"));

	mapStudent1.insert(unordered_multimap<int, string>::value_type (2, "student_two"));   //这样插入也可以，但是注意key是Unique的

	mapStudent1.insert(make_pair<int, string>(3, "student_three"));

	mapStudent1.insert(make_pair<int, string>(3, "student_three"));

	//mapStudent.emplace(5,"student_five");  //Have to add the command '-std=c++11' for compiler

	unordered_multimap<int, string>::iterator  iter1;

	for(iter1 = mapStudent1.begin(); iter1 != mapStudent1.end(); iter1++)

	{

		cout<<iter1->first<<"   "<<iter1->second<<endl;

	}

	printf("-------------------------------\n\n");	

	map<int, string> mapStudent2;

	mapStudent2.insert(pair<int, string>(1, "student_one"));

	mapStudent2.insert(pair<int, string>(2, "student_two"));

	mapStudent2.insert(map<int, string>::value_type (2, "student_two"));   //这样插入也可以，但是注意key是Unique的

	mapStudent2.insert(pair<int, string>(3, "student_three"));

	mapStudent2.insert(pair<int, string>(3, "student_three"));

	mapStudent2[4]="hello"; //利用数组插入同样可以，但是效率比较低

	//mapStudent.emplace(5,"student_five");  //Have to add the command '-std=c++11' for compiler

	map<int, string>::iterator  iter2;

	for(iter2 = mapStudent2.begin(); iter2 != mapStudent2.end(); iter2++)

	{

		cout<<iter2->first<<"   "<<iter2->second<<endl;

	}

	printf("-------------------------------\n\n");

    std::unordered_multimap<std::string,std::string> myumm = {

     {"orange","FL"},

     {"strawberry","LA"},

     {"strawberry","OK"},

     {"pumpkin","NH"} };

    for (auto& x: {"orange","lemon","strawberry"}) {

      std::cout << x << ": " << myumm.count(x) << " entries.\n";

    }

	printf("-------------------------------\n\n");

	typedef std::unordered_multimap<std::string,std::string> stringmap;

    stringmap myumm1 = {

     {"orange","FL"},

     {"strawberry","LA"},

     {"pumpkin","NH"},

     {"strawberry","OK"}

    };

	cout<<"All entries are:"<<endl;

	stringmap::iterator  iter3;

	for(iter3 = myumm1.begin(); iter3 != myumm1.end(); iter3++)

	{

		cout<<iter3->first<<"   "<<iter3->second<<endl;

	}

    std::cout << "Entries with strawberry:";

    auto range = myumm1.equal_range("strawberry");

    for_each (

      range.first,

      range.second,

      [](stringmap::value_type& x){std::cout << " " << x.second;}

    );

	return 0;

}