map的用法

#include <iostream>using namespace std;#include <map>#include <string>template<typename T> void PrintContainer( T container ){T::iterator iter = container.begin();for( ; iter != container.end() ; ++iter){cout<<iter->first<<" , "<<iter->second<<endl;}cout<<endl;}void main(){//创建一个新的map，其中不含任何元素map<int,string> map1;// int 类型的key  ， string类型的valuemap1[0] = "Yao";map1[2] = "Shun";map1[1] = "Yu";PrintContainer(map1);//以op为准则生成一个空的mapmap<int,string,greater<int>> map2;// less<key>:以key为准则升序map2[0] = "Tom";// greater<key>:以key为准则降序map2[3] = "Jerry";map2[2] = "Rose";map2[1] = "Jacky";map2[5] = "Lily";map2[4] = "lucy";map2[6] = "David";PrintContainer(map2);//根据一个已有的map产生一个新的mapmap<int,string>map3(map1);//排序准则不同的两种map容器，PrintContainer(map3);//不能互相产生新的对象//由[beg，end)区间内的元素生成一个新的mapmap<int,string,greater<int>> map4(++(map2.begin()),--(map2.end()));PrintContainer(map4);////map的析构函数//map1.~map();//map2.~map();//map3.~map();//map4.~map();cout<<"map1中元素个数为："<<map1.size()<<endl;cout<<"map2中元素个数为："<<map2.size()<<endl;cout<<"map3中元素个数为："<<map3.size()<<endl;cout<<"map4中元素个数为："<<map4.size()<<endl;//====map的find函数:在容器中根据key寻找某个元素====int key = 8;map<int,string,greater<int>>::iterator iter = map4.find(key);if(iter != map4.end() )cout<<"找到的数据为："<<iter->first<<" , "<<iter->second<<endl;elsecout<<"不存在key为"<<key<<"的元素"<<endl;//====在容器中根据value寻找某个元素====string value = "Jerryr";bool bIsFind = false;map<int,string,greater<int>>::iterator serach = map4.begin();for( ; serach!= map4.end() ; ++serach){if( value == serach->second ){bIsFind = true;cout<<value<<"所对应的key为："<<serach->first<<endl;}}if(!bIsFind)cout<<"容器中没有value为"<<value<<"的元素"<<endl;//====count( n )函数返回容器中key为n的元素个数====int n = 2 ;cout<<"map4中key为"<<n<<"的元素的个数为："<<map4.count(n)<<endl;//============lower_bound(key)函数============cout<<"========lower_bound(key)函数========"<<endl;map<int,string,greater<int>>::iterator index;index = map4.lower_bound(3);//返回键值>=3的第一个元素的迭代器cout<<index->first<<" , "<<index->second<<endl;//============upper_bound(key)函数============cout<<"========upper_bound(key)函数========"<<endl;map<int,string,greater<int>>::iterator big;big = map4.upper_bound(3);//返回键值>3的第一个元素的迭代器cout<<big->first<<" , "<<big->second<<endl;//========map的insert(element)函数===========cout<<"========map的insert(element)函数==========="<<endl;map4.insert( map<int,string,greater<int>>::value_type(0,"John"));map4.insert( pair<int,string>(6,"Mogen") );map4.insert( make_pair(7,"Sniper") );PrintContainer(map4);//=====清空map1内的数据map1.clear();cout<<"map1中元素个数为："<<map1.size()<<endl;system("pause");}