如何在C ++中使用迭代器更改vector中每个elmement的值

Question

I wrote the following program to initialize a vector of Person . But the id of the Person objects does not change. This really confuses me. Can somebody give me an explanation?

#include <iostream>
#include <vector>
#include <string>
#include "Person.h"

using namespace std;
int main()
{
    vector<Person>* pv = new vector<Person>(5,Person(0));
    int i = 0;
    for(Person person : *pv)
    {
        person.id = i++;
    }

    for(Person person : *pv)
    {
        cout<< person.id << endl;
    }

    return 0;
}

with person.h like this

#include <string>

class Person
{
  public:
    int id;
    std::string name;
    Person(int d);
};

Answer 1

In this loop you need to iterate by reference or you will be assigning to the id of a copy of the Person in the vector, not the actual Person in the vector.

for(Person& person : *pv)
{
    person.id = i++;
}