Hi,
can anyone tell need for virtual destructor.


Thanks,
Prasath.K

When classes are inherited, we need to make the base class destructor virtual – to make sure when the object is destroyed, all the derived class destructors also called. Otherwise the derived class destructors are not called because the there is compile time binding of the destructor pointer to the base class destructor.

these are the following reasons to use virtual destructors:-

1. Without a virtual destructor, the proper destructor may not be
called:

struct B {~B();};
struct D : B {~D();};
B* b = new D;
delete b; // <--------- Will not call D::~D() !!!!!

2. Without a virtual destructor, operator delete(void*, size_t) may
not be called with the correct size.

struct B {~B(); operator delete(void*, size_t);};
struct D : B {~D();};
B* b = new D;
delete b; // <--------- Will call operator delete(void*, size_t) with
// the size of B not the size of D!!!

3. Without a virtual destructor, and when MI is used, operator
delete(void*) or operator delete (void*, size_t) may be called with
the wrong address.

struct B {~B();};
struct A {};
struct D : A, B {~D();};
B* b = new D;
delete b; // <--------- May not pass to operator delete the address
// that was returned by operator new!!!


Thank u...it may help u