map遍历

map遍历

测试代码：

#include<bits/stdc++.h>
using namespace std;
void show(map<int,string>& mp)
{
    map<int,string>::iterator iter=mp.begin();
    while(iter!=mp.end())
    {
        cout<<iter->first<<" "<<iter->second<<endl;
        iter++;
    }
    cout<<endl;
}
int main()
{
    //构造 map
    map<int,string> mp;
    mp.insert({5,"map 5"});//使用{}
    mp.insert({6,"map 6"});//使用{}
    mp.insert({7,"map 7"});//使用{}
    mp.insert({8,"map 8"});//使用{}
    mp.insert({0,"map 0"});//使用{}
    mp.insert({1,"map 1"});//使用{}
    mp.insert({2,"map 2"});//使用{}
    mp.insert({3,"map 3"});//使用{}
    mp.insert({4,"map 4"});//使用{}


    //map的遍历
    for(auto& it:mp) //auto自动识别为迭代器类型
    {
        // cout<<it->second<<endl;
        cout<<it.second<<endl;
    }
    cout<<endl;
    //正向迭代器：
    map<int,string>::iterator iter=mp.begin();
    while(iter != mp.end())
    {
        cout<< " first "<< iter->first << " second "<<iter->second<<std::endl;
        iter++;
    }
    cout<<endl;
    for(iter=mp.begin();iter!=mp.end();iter++){
        cout<< " first "<< iter->first << " second "<<iter->second<<std::endl;
    }
    cout<<endl;

    //反向迭代器：
    map<int,string>::reverse_iterator itera=mp.rbegin();
    while(itera != mp.rend())
    {
        cout<< " first "<< itera->first << " second "<<itera->second<<std::endl;
        itera++;
    }
    return 0;
}

运行结果：

map 0
map 1
map 2
map 3
map 4
map 5
map 6
map 7
map 8

 first 0 second map 0
 first 1 second map 1
 first 2 second map 2
 first 3 second map 3
 first 4 second map 4
 first 5 second map 5
 first 6 second map 6
 first 7 second map 7
 first 8 second map 8

 first 0 second map 0
 first 1 second map 1
 first 2 second map 2
 first 3 second map 3
 first 4 second map 4
 first 5 second map 5
 first 6 second map 6
 first 7 second map 7
 first 8 second map 8

 first 8 second map 8
 first 7 second map 7
 first 6 second map 6
 first 5 second map 5
 first 4 second map 4
 first 3 second map 3
 first 2 second map 2
 first 1 second map 1
 first 0 second map 0