c++中map按key和value排序

 ```
 #include<iostream>
 #include<algorithm>
 #include<vector>
 #include<map>
 #include<set>
 using namespace std;

 /*按key升序*/
 void test01(){
     map<string,int,less<string> > map1;
     map1.insert(pair<string,int>("aba",));
     map1.insert(pair<string,int>("aaa",));
     map1.insert(pair<string,int>("ddd",));
     map1.insert(pair<string,int>("ccc",));

     for(map<string,int>::iterator it=map1.begin(); it!=map1.end(); it++ ){
         cout<<(*it).first<<" : "<<(*it).second<<endl;
     }
 }
 /*按key降序*/
 void test02(){
     map<string,int,greater<string> > map1;
     map1.insert(pair<string,int>("aba",));
     map1.insert(pair<string,int>("aaa",));
     map1.insert(pair<string,int>("ddd",));
     map1.insert(pair<string,int>("ccc",));

     for(map<string,int>::iterator it=map1.begin(); it!=map1.end(); it++ ){
         cout<<(*it).first<<" : "<<(*it).second<<endl;
     }
 }
 /*----------------------------------------------------*/
 /*编写类或者结构体按key升序或者降序*/
 class flag{
 public:
     bool operator()(string v1,string v2){
         return v1<v2;
     }
 };

 void test03(){
     map<string,int,flag> map1;
     map1.insert(pair<string,int>("aba",));
     map1.insert(pair<string,int>("aaa",));
     map1.insert(pair<string,int>("ddd",));
     map1.insert(pair<string,int>("ccc",));

     for(map<string,int>::iterator it=map1.begin(); it!=map1.end(); it++ ){
         cout<<(*it).first<<" : "<<(*it).second<<endl;
     }
 }
 /*-------------------------------------------------------*/
 /*自定义编写类或者函数或者结构体进行值排序*/
 /*自定义函数编写不用()，自定义类或者结构体需要()*/
 bool flag_2(pair<string,int> o1,pair<string,int> o2){
     return o1.second>o2.second;
 }
 class flag_2{
 public:
     bool operator()(pair<string,int> o1,pair<string,int> o2){
         return o1.second>o2.second;
     }
 };
 struct flag_2{
     bool operator()(pair<string,int> o1,pair<string,int> o2){
         return o1.second<o2.second;
     }
 };
 void test04(){
     map<string,int> map1;
     map1.insert(pair<string,int>("aba",));
     map1.insert(pair<string,int>("aaa",));
     map1.insert(pair<string,int>("ddd",));
     map1.insert(pair<string,int>("ccc",));

     //利用vector进行value排序
     vector< pair<string,int> > dic1(map1.begin(),map1.end());
     sort(dic1.begin(),dic1.end(),flag_2());

     for(int i=; i<dic1.size(); i++ ){
         cout<<dic1[i].first<<" "<<dic1[i].second<<endl;
     }
 }
 int main(){
     //test01();
     //test02();
     //test03();
     test04();

     return ;
 }

 ```