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In C++, a constructor is a special member function of a class which is used to create and initialize its objects. A destructor is also a special member function, but contrary to the working of a constructor, a destructor is used to destroy the objects of a class and to clean up their storage space, because let's say, these objects are no longer required and accessible.



Some important features of a destructor are-

• A destructor must always have the same name as its class, preceded by the tilde ~ sign.
• A destructor cannot have a return type.
• A destructor can only have one access modifier, which is public.
• A destructor is never inherited or overridden as it's not a simple function of a class.

When a destructor is called?

A destructor is automatically called by the compiler when a program ends its execution or as soon as the closing brace } of a block or a function is encountered, and in this case the compiler calls the destructor which destroys all the objects created within that particular block/function.

An example of destructor


Let's see an example in which we will create multiple objects of a class within the main() function by calling the constructor, and upon the exit of the main() function, the compiler will automatically call the destructor of the class, which destroys all the objects created by the constructor.



//C++ An example of destructor


#include<iostream>

using namespace std;

class A
{
public:

//A no-argument constructor
A()		
{ 
	cout << "Constructor called" <<"\n";
}


//A destructor
~A()		
{
	cout <<Destructor called" <<"\n";
}
};


int main()
{
	// Calling a no-argument constructor to create the objects of the class A
	A ob1, ob2, ob3;	
}





Output-




Constructor called
Constructor called
Constructor called
Destructor called
Destructor called
Destructor called





Program Analysis



• In this code above, we have created a class A with a no-argument constructor and a destructor.
• Next, we have created three objects of this class, which automatically calls the constructor(once for each object).
• Finally, upon the encountering the closing brace } of the main function, the compiler automatically calls the destructor(once for each object to be destroyed).





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Another example of destructor


Let's see another example in which we are going to create objects at two different places:
• Within a user-defined function.
• Within a block in the main() function.
These objects will automatically be destroyed by the destructor of the class at the closing brace } of the function and the block in which they were created.



//C++ Another example of destructor


#include<iostream>

using namespace std;

class A
{
public:

//A no-argument constructor
A()		
{ 
	cout << "Constructor called" <<"\n";
}


//A destructor
~A()		
{
	cout << "Destructor called" <<"\n";
}

void fun()
{
	A ob;
}
};


int main()
{
	// Calling a no-argument constructor to create a object of class A
	A ob1; 
	
	//Calling a user-defined function
	ob1.fun();
	
	//A local block
	{	
		A ob2;
	}
}





Output-




Constructor called
Constructor called
Constructor called
Destructor called
Destructor called
Destructor called





Program Analysis



• In this code above, we have created a class A with a no-argument constructor and a destructor.
• Next, we have created an object of this class, using which we have called the function fun(), in which we have created a local object, which is automatically destroyed by the destructor upon the encountering the closing brace } of the function fun().
• Next, we have created an object within a local block in the main() function and upon the end of this block, the compiler automatically calls the destructor to destroy its local object.






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