Explain the role of constructor and destructor in a class. Write the appropriate syntax for the copy constructor and parameterized constructors.

Constructor:

• Definition: A constructor is a special member function of a class that is executed whenever we create new objects of that class.
• Role:
  • Initializes the data members of the class.
  • Allocates memory for the object.
  • Performs other necessary operations for object creation.

• Syntax:

  class MyClass {
  public:
      MyClass(); // Default constructor
      MyClass(int x); // Parameterized constructor
      // Other members...
  };
  

Destructor:

• Definition: A destructor is a special member function of a class that is executed whenever an object of that class is destroyed.
• Role:
  • Frees the memory allocated for the object.
  • Performs other necessary operations for object destruction.

• Syntax:

  class MyClass {
  public:
      ~MyClass(); // Destructor
      // Other members...
  };
  

Copy Constructor:

• Definition: A copy constructor is a special member function that is used to create a new object of a class by copying values from an existing object of the same class.
• Role:
  • Creates a new object that is a copy of an existing object.
  • Initializes the data members of the new object with the values of the corresponding data members of the existing object.

• Syntax:

  class MyClass {
  public:
      MyClass(); // Default constructor
      MyClass(const MyClass& other); // Copy constructor
      // Other members...
  };
  

Parameterized Constructor:

• Definition: A parameterized constructor is a special member function that is used to create a new object of a class by passing values to its constructor.
• Role:
  • Creates a new object and initializes its data members with the specified values.

• Syntax:

  class MyClass {
  public:
      MyClass(); // Default constructor
      MyClass(int x); // Parameterized constructor
      // Other members...
  };
  

Consider the following example:

class Person {
public:
    Person() { // Default constructor
        name = "John Doe";
        age = 20;
    }

    Person(string name, int age) { // Parameterized constructor
        this->name = name;
        this->age = age;
    }

    ~Person() { // Destructor
        cout << "Person object destroyed" << endl;
    }

    // Other member functions...

private:
    string name;
    int age;
};

In this example, the Person class has a default constructor, a parameterized constructor, and a destructor.

• The default constructor initializes the name and age data members to default values.
• The parameterized constructor takes two arguments, name and age, and initializes the corresponding data members of the newly created object with these values.
• The destructor prints a message to the console when an object of the Person class is destroyed.

When we create a Person object using the default constructor, the following code will be executed:

Person person1; // Default constructor is called

This will create a Person object with the name "John Doe" and age 20.

When we create a Person object using the parameterized constructor, the following code will be executed:

Person person2("Jane Doe", 30); // Parameterized constructor is called

This will create a Person object with the name "Jane Doe" and age 30.

When we destroy a Person object, the following code will be executed:

person1.~Person(); // Destructor is called

This will print the message "Person object destroyed" to the console.