How to allow user input to indicate a size of an array? The array has to be a dynamically allocated array of type Person which is the class

Question

This is what I have so far, and it does give me the desired output, but I couldn't figure out how to use a dynamically allocated array. I wanted to figure out the problem without that first, so I can figure out how the rest of the code would work.

Instead of using a constant variable for the size of the array, how can I have the user input a desired amount that would then be used for the array?

class Person
{
private:
  string name;
  int age;

public:
  // Default constructor
  Person()
  {
    name = " ";
    age = 0;
  } 

  Person(string name1, int age1)
  {
     name = name1;
     age = age1;
  }
  
  int getAge() { return age; }
  string getName() { return name; }
  
  // Mutator functions to set name and age
  void setName(string name1);
  void setAge(int age1);
};

int lengthOfName(Person *p);

// Main Function
int main()
{   
  string name;
  int age;
  const int SIZE = 3;

  Person personArray[SIZE];

  for (int i = 0; i < SIZE; i++)
  {
    cout << "Enter the name:" << endl;
    cin >> name;
    personArray[i].setName(name);

    cout << "Enter the age:" << endl;
    cin >> age;
    personArray[i].setAge(age);
  }

  for (int i = 0; i < SIZE; i++)
  {
      cout << "The name " << personArray[i].getName();
      cout << " has length: " << lengthOfName(&personArray[i]) << endl;
  }
}

// Returns the number of characters in a person's name *
int lengthOfName(Person *p)
{
  string name = p->getName();
  return name.length();
}

// Mutator function that sets variable name
void Person::setName(string name1)
{
  name = name1;
}

// Mutator function that sets variable age
void Person::setAge(int age1)
{
  age = age1;
}

Answer 1

Dynamic arrays are allocated using the new[] operator, and freed using the delete[] operator, eg:

size_t size;
cin >> size;

Person *personArray = new Person[size];
...
delete[] personArray;

However, you should use std::vector instead and let it manage the memory for you:

#include <vector>

size_t size;
cin >> size;

std::vector<Person> personArray(size);
...