samedi 18 juillet 2020

Copy constructor called multiple times for custom map values

I've just started using maps in C++, I implemented this piece of code where I've used custom datatype for map values. But I haven't understood the copy constructor part. It's being called multiple times only when I use

person.insert(make_pair(55,Person("Bob",23)));
person.insert(make_pair(35,Person("Bill",25)));

Can someone kindly explain me the working of the copy constructor in this code ??

#include<iostream>
#include<map>

using namespace std;

class Person{
    private:
        string name;
        int age;
    
    public:
        Person(const Person &other){
            cout<<"Copy Constructor Running !!"<<endl;
            name=other.name;
            age=other.age;
        }
        Person():name(""),age(0){
            
            
        }
        Person(string name,int age):name(name), age(age){
            
           
        }
        void print(){
            cout<<name<<" : "<<age<<endl;
        }
};

int main(){

    map<int,Person> person;
    person[50]=Person("Mike",19);
    person[20]=Person("Julia",20);
    person[30]=Person("Raj",29);
    person[10]=Person("Kendra",20);
    person[70]=Person("Rahul",18);

    person.insert(make_pair(55,Person("Bob",23)));
    person.insert(make_pair(35,Person("Bill",25)));


    
    for(auto it=person.begin();it!=person.end();it++){
    cout<<it->first<<" : ";
    it->second.print();
    }
    
   
   

    return 0;
}

OUTPUT:

Copy Constructor Running !!
Copy Constructor Running !!
Copy Constructor Running !!
Copy Constructor Running !!
10 : Kendra : 20
20 : Julia : 20
30 : Raj : 29
35 : Bill : 25
50 : Mike : 19
55 : Bob : 23
70 : Rahul : 18

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