c++学习之set容器-自定义数据类型指定排序规则

存放自定义数据类型必须要指定排序规则

#include <iostream>
#include <queue>
#include <algorithm>
#include <string>
#include <set>
using namespace std;

class Person
{
  public:
    Person(string name,int age)
    {
        this->m_Name = name;
        this->m_Age = age;
    }

    string m_Name;
    int m_Age;
};

class myCompare
{
  public:
    bool operator()(const Person  &p1,const Person &p2)
    {
      return p1.m_Age > p2.m_Age;
    }
};

void print(const set<Person,myCompare>& s)
{
    for(set<Person,myCompare>::const_iterator it = s.begin(); it != s.end(); it++)
    {
        cout<< (*it).m_Name <<" " << (*it).m_Age <<endl;
    }
}

void test()
{
   set<Person,myCompare>s;
   Person p1("lcl",23);
   Person p2("xqq",20);
   Person p3("hqq",23);
   Person p4("wxr",22);
   Person p5("lcl",22);

   s.insert(p1);
   s.insert(p2);
   s.insert(p3);
   s.insert(p4);
   s.insert(p5);

   print(s);
}

int main()
{ 
    test();
    return 0;
}

输出结果

代码示例
名字相同，按照年龄排序

#include <iostream>
#include <algorithm>
#include <string>
#include <set>
using namespace std;

class Person
{
  public:
    Person(string name,int age)
    {
        this->m_Name = name;
        this->m_Age = age;
    }

    // Person(const Person &p)
    // {
    //     this->m_Name = p.m_Name;
    //     this->m_Age = p.m_Age;
    // }
/*
    bool operator<(const Person &rhs) const
    {
        if(!m_Name.compare(rhs.m_Name)) 
        {
          return m_Age<rhs.m_Age;
        }
      else return m_Name.compare(rhs.m_Name) < 0;
    }
*/
    // Person& operator = (const Person &rhs)
    // {
    //     m_Name = rhs.m_Name;
    //     m_Age = rhs.m_Age;
    // }

    string m_Name;
    int m_Age;
};

 class myCompare
 {
   public:
     bool operator()(const Person  &p1,const Person &p2) 
     {
       if(!p1.m_Name.compare(p2.m_Name)) {  //如果名字相等，则按从大到小排列
           return p1.m_Age>p2.m_Age;
       }
       else return p1.m_Name.compare(p2.m_Name) < 0;
     }
 };

// void print(const set<Person,myCompare>& s)
// {
//     for(set<Person,myCompare>::const_iterator it = s.begin(); it != s.end(); it++)
//     {
//         cout<< (*it).m_Name <<" " << (*it).m_Age <<endl;
//     }
// }

void print(const set<Person,myCompare> &s) 
{
    for(set<Person>::const_iterator it = s.begin(); it != s.end(); it++)
    {
        cout << (*it).m_Name << " " << (*it).m_Age <<endl;
    }
}

void test()
{
   set<Person,myCompare> s;
   //set<Person,myCompare>s;
   Person p1("lcl",23);
   Person p2("xqq",20);
   Person p3("hqq",23);
   Person p4("wxr",22);
   Person p5("lcl",22);

   s.insert(p1);
   s.insert(p2);
   s.insert(p3);
   s.insert(p4);
   s.insert(p5);
   print(s);
}

int main()
{ 
    test();
    return 0;
}

结果输出