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C++ and OOPS Sample Question

8. class some{
   public:
   	~some()
   	{
   		cout«"some's destructor"«endl;
   	}
   };
   
   void main()
   {
   	some s;
   	s.~some();
   }

   Answer :

   some's destructor
   some's destructor

   Explanation:

   Destructors can be called explicitly. Here 's.~some()' explicitly calls the destructor of 's'. When main() returns, destructor of s is called again, hence the result.

9. #include ‹iostream.h›
   
   class fig2d
   {
   	int dim1;
   	int dim2;
   
   public:
   	fig2d() { dim1=5; dim2=6;}
   
   	virtual void operator«(ostream & rhs);
   };
   
   void fig2d::operator«(ostream &rhs)
   {
   	rhs «this->dim1«" "«this->dim2«" ";
   }
   
   /*class fig3d : public fig2d
   {
   	int dim3;
   public:
   	fig3d() { dim3=7;}
   	virtual void operator«(ostream &rhs);
   };
   void fig3d::operator«(ostream &rhs)
   {
   	fig2d::operator «(rhs);
   	rhs«this -> dim3;
   }
   */
   
   void main()
   {
   	fig2d obj1;
   //	fig3d obj2;
   
   	obj1 « cout;
   //	obj2 « cout;
   }

   Answer :

   5 6

   Explanation:

   In this program, the « operator is overloaded with ostream as argument. This enables the 'cout' to be present at the right-hand-side. Normally, 'cout' is implemented as global function, but it doesn't mean that 'cout' is not possible to be overloaded as member function.

   Overloading « as virtual member function becomes handy when the class in which it is overloaded is inherited, and this becomes available to be overrided. This is as opposed to global friend functions, where friend's are not inherited.

10. class opOverload{
    public:
    	bool operator==(opOverload temp);
    };
    
    bool opOverload::operator==(opOverload temp){
    	if(*this  == temp ){
    		cout«"The both are same objects\n";
    		return true;
    	}
    	else{
    		cout«"The both are different\n";
    		return false;
    	}
    }
    
    void main(){
    	opOverload a1, a2;
    	a1= =a2;
    }

    Answer :

    Runtime Error: Stack Overflow

    Explanation:

    Just like normal functions, operator functions can be called recursively. This program just illustrates that point, by calling the operator == function recursively, leading to an infinite loop.

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