Question

Water default and overloaded constructor and destructor for a class Person with attributes name, age, height, weight. One of the constructors must initialize only the name. What is the purpose of the destructor? Explain with an example. Why do we need Private member Functions

Answer 1

7.)

#include<iostream>
using namespace std;
class Person {
   public:
       std::string name;
       int age;
       int height;
       int weight;
   public:
       Person(); // defalut constructor
       Person(std::string name_local){ // overloaded constructor which intiates name only.
           name = name_local;
       }
       Person(int age,int height, int weight){ // Overloaded constructor which intiates remaining three.
           age = age;
           height = height;
           weight = weight;
       }
       ~Person(){                       // Destructor for class Person
           cout << "Destructor called";
       }
};
int main(){
}

8.)

"Destructor" of a class in cpp is inverse of constructor functions. They are called when objects are destroyed (deallocated). We declare destructor for a class by preceding the class name with a tilde(~). For Example Person is the class. Then destructor for this class is ~Person().The destructor is commonly used to "clean up" when an object is no longer necessary.

Destructor of a class is used to clear up or to free the memory that is used by that class from intiation of a object until destructor is called. The destructor has a special role in releasing managed and unmanaged resources.

Example :

#include <iostream>

struct Member
{
int index;

Member ( int index ) : index ( index ) {}

~Member()
{
std::cout << "~Member " << index << std::endl;
}
};

int main()
{
Member a1(1);
Member* point;
Member a2(2);
point = new Member(3);
  
delete point; // calls the destructor of a3
}

9.)

The idea of classes is to restrict user access. We don't want the user to access data or functions unnecessarily.

Member data are made private while functions(or methods) are made public. There might be instances where you might want to make certain functions private. You may not want the user to directly access these functions. Private functions can only be called from within public member functions.

Let’s take the example of the class ‘batsman’. After every match the user will enter the batsman’s new score and then he will have to call two functions to update the batsman’s record (i.e. the user has to call update_best ( ) and update_worst ( )). It is unnecessary to bother the user with this kind of a double function call. Why should the user access these two functions directly? Instead of this, we could define another function called update ( ) which will call update_best ( ) and update_worst ( ). In this way the user needs to only call one function after every match.