Answer Posted / chandra

Vitual destructor is used

(1) whenever the base class object pointer points to
derived class object,and is being created using new.
i.e class base - base class
in main - base bptr;
class derived - derived class
in main - bptr = new derived();

Then whenever we use "delete bptr" at runtime always the
memory of bptr is freed but not derived because here the
pointer is of type base and not of derived.

Note: The destructor that gets invoked is the one that
associated with the type of the object.

Simple rule of thumb: Make your destructor virtual if your
class has any virtual functions.

Example:
#include <iostream.h>
class Base
{
public:
Base(){ cout<<"Constructor: Base"<<endl;}
virtual ~Base(){ cout<<"Destructor : Base"<<endl;}
};
class Derived: public Base
{
//Doing a lot of jobs by extending the functionality
public:
Derived(){ cout<<"Constructor: Derived"<<endl;}
~Derived(){ cout<<"Destructor : Derived"<<endl;}
};
void main()
{
Base *Var = new Derived();
delete Var;
}

Describe friend function & its advantages.

719

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Can you pass an array to a function in c++?

545

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Given the following seqment of code containing a group of nested if instructions: y = 9; if ((x==3) || (x == 5)) y++; else if (x == 2) y *= 2; else if (x == ) y-= 7; else y = 8; if the value of x is 4 before the nested IFs are executed, what is the value of y after the nested IFs are executed?

1589

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What are the extraction and insertion operators in c++? Explain with examples.

656

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Explain unexpected() function?

589

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What is a singleton c++?

552

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Evaluate the following expression as C++ would do :8 * 9 + 2 * 5 a) 82 b) 79 c) 370 d) list

618

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What is the extension of c++?

518

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the maximum length of a character constant can be a) 2 b) 1 c) 8

602

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Explain class invariant.

589

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What is virtual function? Explain with an example

593

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What is the difference between while and do while loop? Explain with examples.

604

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What is ios in c++?

650

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What are separators in c++?

628

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Is map thread safe c++?

636

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