目录

1.map的构造和赋值 

2.map的大小和交换

3.map的插入和删除

4.map的查找和统计

5.map的排序

---

1.map的构造和赋值 

#include<bits/stdc++.h>
using namespace std;void print(map<int,int> &mp)
{for(map<int,int>::iterator it = mp.begin(); it != mp.end(); it++){cout << it -> first << ' ' << it -> second;cout << endl;}cout << endl;
}int main()
{map<int,int> mp;mp.insert(pair<int,int>(1,90));mp.insert(pair<int,int>(2,950));mp.insert(pair<int,int>(7,920));mp.insert(pair<int,int>(5,10));mp.insert(pair<int,int>(6,80));//按照key的值进行排序print(mp);return 0;
}

 

2.map的大小和交换

#include<bits/stdc++.h>
using namespace std;void print(map<int,int> &mp)
{for(map<int,int>::iterator it = mp.begin(); it != mp.end(); it++){cout << it -> first << ' ' << it -> second;cout << endl;}cout << endl;
}int main()
{map<int,int> mp;mp.insert(pair<int,int>(1,90));mp.insert(pair<int,int>(2,950));mp.insert(pair<int,int>(7,920));mp.insert(pair<int,int>(5,10));mp.insert(pair<int,int>(6,80));//按照key的值进行排序print(mp);cout << mp.empty() << endl;cout << mp.size() << endl;map<int,int>mp1;mp1.swap(mp);print(mp1);return 0;
}

3.map的插入和删除

#include<bits/stdc++.h>
using namespace std;void print(map<int,int> &mp)
{for(map<int,int>::iterator it = mp.begin(); it != mp.end(); it++){cout << it -> first << ' ' << it -> second;cout << endl;}cout << endl;
}int main()
{map<int,int> mp;mp.insert(pair<int,int>(1,90));mp.insert(pair<int,int>(2,950));mp.insert(make_pair(7,920));mp.insert(pair<int,int>(5,10));mp[6] = 80;//按照key的值进行排序print(mp);mp.erase(6);//按照key删除mp.erase(mp.begin());//也可以传迭代器进行删除print(mp);mp.clear();print(mp);return 0;
}

4.map的查找和统计

#include<bits/stdc++.h>
using namespace std;void print(map<int,int> &mp)
{for(map<int,int>::iterator it = mp.begin(); it != mp.end(); it++){cout << it -> first << ' ' << it -> second;cout << endl;}cout << endl;
}int main()
{map<int,int> mp;mp.insert(pair<int,int>(1,90));mp.insert(pair<int,int>(2,950));mp.insert(make_pair(7,920));mp.insert(pair<int,int>(5,10));mp[6] = 80;map<int,int>::iterator it = mp.find(5);//从前往后找map里有没有key为5的，没找到的话迭代器就在mp.end()处if(it != mp.end()) cout << "找到了" << endl;cout << mp.count(7) << endl;//输出有几个key为7的数，这里只有一个return 0;
}

5.map的排序

改成从大到小 

#include<bits/stdc++.h>
using namespace std;class cmp
{
public:bool operator()(int v1,int v2){return v1 > v2;}
};int main()
{map<int,int,cmp> mp;mp.insert(pair<int,int>(1,90));mp.insert(pair<int,int>(2,950));mp.insert(make_pair(7,920));mp.insert(pair<int,int>(5,10));mp[6] = 80;for(map<int,int,cmp>::iterator it = mp.begin(); it != mp.end(); it++){cout << it -> first << ' ' << it -> second << endl;}return 0;
}