inheritance - Why can't class be destructed in polymorphism C++ -

i have problem using polymorphism. code here:

class { public:     a() {cout << "construct a" << endl;}     virtual ~a() {cout << "destroy a" << endl;} };  class b : public a{ public:     b() {cout << "construct b" << endl;}     ~b() {cout << "destroy b" << endl;} }; void main() {     *p = new b; } 

the result is:

construct construct b 

why 'p' can not destroyed or may wrong somewhere. thanks.

you need invoke

delete p; 

to delete pointer , call destructor. dynamically allocated objects not have destructor called automatically, that's why need invoke delete operator, first invokes destructor calls operator delete release memory.