关联容器 multimap

//multimap会自动按照键值为所有元素排序，将键值相同的元素放在一起
//能够对元素进行快速访问，因为它是树形结构。

#include<iostream>
#include<string>
#include<algorithm>
#include<map>

void output( std::pair<const int,std::string> &s){
std::cout<<"   "<<s.first<<"   "<<s.second<<std::endl;
}

typedef int KeyType;
typedef std::pair<const KeyType,std::string>Pair;
typedef std::multimap<KeyType,std::string>MapCode;

int main(void){
using namespace std;
MapCode  codes;

codes.insert(Pair(415,"墨西哥"));
codes.insert(Pair(718,"布鲁克林"));
codes.insert(Pair(510,"乌克兰"));
codes.insert(Pair(718,"夏威夷群岛"));
codes.insert(Pair(718,"冰岛"));
codes.insert(Pair(415,"洛杉矶"));
codes.insert(Pair(510,"加州"));

cout<<"Number of cities with area code 415:"<<codes.count(415) <<endl;
cout<<"Number of cities with area code 510:"<<codes.count(510) <<endl;
cout<<"Number of cities with area code 718:"<<codes.count(718) <<endl;

cout<<"Area Code of City:\n";
for_each(codes.begin(),codes.end(),output);

//ostream_iterator<Pair,char> out(cout,"  ");
//copy(codes.begin(),codes.end(),out);

pair<MapCode::iterator,MapCode::iterator> range=codes.equal_range(718);
cout<<"Cities with area code 718：\n";
MapCode::iterator it;
for(it=range.first;it!=range.second;++it){
cout << (*it).second << endl;

}

return 0;

}