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| //
#include <stdio.h>
#include <iostream>
#include <map>
#include <typeinfo>
using namespace std;
template<class K>
void print(const string s,const K& mmap){
cout<<s<<endl;
for(auto& a:mmap){
cout<<"{"<<a.first<<","<<a.second<<"} ";
}
cout<<endl;
}
int main(){
multimap<int,char> dict {
{1,'A'},
{2,'B'},
{2,'C'},
{3,'D'},
{3,'E'},
{2,'F'}
};
//通过empty()来判断multimap是否为空
cout<<"dict.empty() "<<dict.empty()<<endl;
//通过size()来判断元素个数
cout<<"dict.size() "<<dict.size()<<endl;
print("插入前 size = "+to_string(dict.size()),dict);
// 通过insert插入元素
dict.insert({4,'G'});
dict.insert(pair<int, char>(4,'F'));
dict.insert(make_pair(4, 'H'));
dict.insert({{5,'I'},{5,'J'}});
print("插入后 size = "+to_string(dict.size()),dict);
// 通过erase来删除特定key的元素,参数可以是key，也可以是一个iterator
dict.erase(1);
print("删除key=1后 size = "+to_string(dict.size()),dict);
// 返回类型是pair<iterator,iterator>,仅仅返回符合条件的pair
auto range = dict.equal_range(2);
//cout<<typeid(range).name()<<endl; //pair类型
cout<<"equal_range(2) "<<endl;
for(auto i = range.first;i!=range.second;++i){
cout<<"i.first\t"<<i->first<<"\ti.second\t"<<i->second<<endl;
}
// lower_bound
auto lower = dict.lower_bound(2);
cout<<"lower_bound(2) "<<(lower->first)<<" "<<lower->second<<endl;
// upper_bound
auto upper = dict.upper_bound(2);
cout<<"upper_bound(2) "<<(upper->first)<<" "<<upper->second<<endl;
// equal_range返回的两个pair实际上就是用lower_bound和upper_bound来实现的
cout<<"lower_bound == range.first "<< (lower == range.first)<<endl;
cout<<"upper_bound == range.second "<< (upper == range.second)<<endl;
//通过count来判断key等于给定的值一共有多少个pair
cout<<"count(2) "<<dict.count(2)<<endl;
//这个数量可以通过range的两个iterator来实现查找
cout<<"distance(range.first,range.second) "<<distance(range.first,range.second)<<endl;
//或者使用lower_bound和upper_bound来实现
cout<<"distance(lower,upper)"<<distance(lower, upper)<<endl;
//通过find来判断是否存在key,返回一个iterator,如果有多个key符合条件，不一定会返回哪一个。
auto find2 = dict.find(2);
cout<<"find2 "<<find2->first<<" "<<find2->second<<endl;
//如果通过find来查找的时候没有找到对应的key,那么就会返回dict.end()这个iterator
auto find10 = dict.find(10);
cout<<"find10==dict.end "<<(find10==dict.end())<<endl;
auto a = dict.begin();
cout<<"dict.begin().type "<<typeid(a).name()<<endl;
//关于各类iterator
cout<<"正向遍历dict.begin()->dict.end()"<<endl;
for(auto a = dict.begin(); a!=dict.end(); a++){
// a->second = 'M'; 这里修改就没有问题
cout<<"{"<<a->first<<","<<a->second<<"} ";
}
cout<<"正向遍历，dict.cbegin()->dict.cend()"<<endl;
for(auto a = dict.cbegin(); a!=dict.cend(); a++){
// a -> second = 'N'; 这里修改就有问题，原因是返回的const_iterator是不允许修改的。
cout<<"{"<<a->first<<","<<a->second<<"} ";
}
cout<<endl;
cout<<"反向遍历，dict.rbegin()->dict.rend()"<<endl;
for(auto a = dict.rbegin(); a!=dict.rend(); a++){
cout<<"{"<<a->first<<","<<a->second<<"} ";
}
cout<<endl;
cout<<"反向遍历，dict.rbegin()->dict.rend()"<<endl;
for(auto a = dict.rbegin(); a!=dict.rend(); a++){
cout<<"{"<<a->first<<","<<a->second<<"} ";
}
cout<<endl;
cout<<"反向遍历，dict.crbegin()->dict.crend()"<<endl;
for(auto a = dict.crbegin(); a!=dict.crend(); a++){
cout<<"{"<<a->first<<","<<a->second<<"} ";
}
cout<<endl;
return 0;
}
/* 运行结果
dict.empty() 0
dict.size() 6
插入前 size = 6
{1,A} {2,B} {2,C} {2,F} {3,D} {3,E}
插入后 size = 11
{1,A} {2,B} {2,C} {2,F} {3,D} {3,E} {4,G} {4,F} {4,H} {5,I} {5,J}
删除key=1后 size = 10
{2,B} {2,C} {2,F} {3,D} {3,E} {4,G} {4,F} {4,H} {5,I} {5,J}
equal_range(2)
i.first 2 i.second B
i.first 2 i.second C
i.first 2 i.second F
lower_bound(2) 2 B
upper_bound(2) 3 D
lower_bound == range.first 1
upper_bound == range.second 1
count(2) 3
distance(range.first,range.second) 3
distance(lower,upper)3
find2 2 B
find10==dict.end 1
dict.begin().type NSt3__114__map_iteratorINS_15__tree_iteratorINS_12__value_typeIicEEPNS_11__tree_nodeIS3_PvEElEEEE
正向遍历dict.begin()->dict.end()
{2,B} {2,C} {2,F} {3,D} {3,E} {4,G} {4,F} {4,H} {5,I} {5,J} 正向遍历，dict.cbegin()->dict.cend()
{2,B} {2,C} {2,F} {3,D} {3,E} {4,G} {4,F} {4,H} {5,I} {5,J}
反向遍历，dict.rbegin()->dict.rend()
{5,J} {5,I} {4,H} {4,F} {4,G} {3,E} {3,D} {2,F} {2,C} {2,B}
反向遍历，dict.rbegin()->dict.rend()
{5,J} {5,I} {4,H} {4,F} {4,G} {3,E} {3,D} {2,F} {2,C} {2,B}
反向遍历，dict.crbegin()->dict.crend()
{5,J} {5,I} {4,H} {4,F} {4,G} {3,E} {3,D} {2,F} {2,C} {2,B}
Program ended with exit code: 0
*/
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