https://blog.youkuaiyun.com/jiyi_xiaoli/article/details/76375685 it->first: 关键字
it->second: 该关键字的值
#include<iostream>
#include<cstring>
#include<map>
using namespace std;
int main(){
int a[5];
map<int,int> M;
a[0]=1;M[a[0]]++;
a[1]=2;M[a[1]]++;
a[2]=2;M[a[2]]++;
a[3]=4;M[a[3]]++;
a[4]=4;M[a[4]]++;
map<int,int>::iterator it;
for(it=M.begin();it!=M.end();it++)
cout<<it->first<<' '<<it->second<<endl;
return 0;
}
运行结果