What is destructor in C++ ?

webmaster — Thu, 18 Aug 2022 10:51:24 +0000

In C++ destructor is an instance member function which is invoked automatically whenever an object is going to be destroyed.
A destructor meaning is the last function that is going to be called before an object is destroyed.
If the object is created by using new or the constructor uses new to allocate memory which resides in the heap memory or the free store, the destructor should use delete to free the memory, the thing is to be noted here.
When the objects are destroyed, destructor function is automatically invoked.
Destructor does not have arguments and it cannot be declared as constant or static.
Destructor cannot become a member of the union while with an object of a class.
The programmer cannot access the address of destructor and in public section of class destructor should be declared.
If the object goes out of scope, destructor function is called automatically were the function ends, the program ends, a block containing local variables ends, a delete operator is called.
Destructors have same name as the class preceded by a tilde (~) it doesn’t take any argument and return anything.

Sample Code

#include
               using namespace std;
              class Demo {
                   private:
                   int num1, num2;
                   public:
                   	Demo(int n1, int n2) {
                                   cout<<"Inside Constructor"<                                   num1 = n1;
                                   num2 = n2;
                              }
                             void display() {
                                   cout<<"num1 = "<< num1 <                                   cout<<"num2 = "<< num2 <                             }
                         ~Demo() {
                                  cout<<"Inside Destructor";
                            }
                       };
                      int main() {
                      Demo obj1(30, 50);
                      obj1.display();
                      return 0;
                      }

Output

What is Constructor in C++ ?

webmaster — Thu, 18 Aug 2022 10:41:19 +0000

In C++ constructor is a special type of member function of a class which initializes objects of a class.
Constructor is automatically called when object is created in C++.
It does not have any return type because it is special member function of the class.
In public section of class and it has same name as the class itself.
Copy and parameterized constructors have input arguments, by default constructors don’t have input argument however.
C++ compiler generates a default constructor for object, if we do not specify a constructor.
In constructor there are three types, they are default constructor, parameterized constructor, copy constructor.

Default Constructor

It is the constructor which has no parameters and doesn’t take any argument.

Sample Code

using namespace std;

class construct

{

public:

    int a, b;




    // Default Constructor

    construct()

    {

        a = 30;

        b = 40;

    }

};




int main()

{

    // Default constructor called automatically

    // when the object is created

    construct c;

    cout << "a: " << c.a << endl

         << "b: " << c.b;

    return 1;

}

Output

Parameterized Constructor

It is possible to pass arguments to constructors and these arguments help initialize an object when it is created typically.

Sample Code

using namespace std;

class Point

{

private:

    int x, y;




public:

    // Parameterized Constructor

    Point(int x1, int y1)

    {

        x = x1;

        y = y1;

    }




    int getX()

    {

        return x;

    }

    int getY()

    {

        return y;

    }

};




int main()

{

    // Constructor called

    Point p1(10, 15);




    // Access values assigned by constructor

    cout << "p1.x = " << p1.getX() << ", p1.y = " << p1.getY();




    return 0;

}

Output

Copy Constructor

It is a member function which initializes an object using another object of the same class.

Sample Code

using namespace std;

class point

{

private:

  double x, y;




public:

   

  // Non-default Constructor &

  // default Constructor

  point (double px, double py)

  {

    x = px, y = py;

  }

};




int main(void)

{




  // Define an array of size

  // 10 & of type point

  // This line will cause error

  point a[10];




  // Remove above line and program

  // will compile without error

  point b = point(5, 6);

}

constructor and destructor in c++ - Wikitechy

What is destructor in C++ ?

Sample Code

Output

What is Constructor in C++ ?

Default Constructor

Sample Code

Output

Parameterized Constructor

Sample Code

Output

Copy Constructor

Sample Code

Output