C++ map 遍历

#include <iostream>

#include <map>

using namespace std;

int main(){

    map<int,int> m;

    for (int i = ; i < ; i++){

        m[i] = i*i;

    }

    map<int,int>::iterator iter;

    iter = m.begin();

    while(iter != m.end()){

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

        iter++;

    }

    for (iter = m.begin();iter != m.end(); iter++){

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

    }

    for(auto &it : m){

        cout << it.first << "-" << it.second <<endl;

    }

    return ;

}