Question

How does container object like vector in stl get destroyed even though they are created in heap?

EDIT

If the container holds pointers then how to destroy those pointer objects

Answer 1

An STL container of pointer will NOT clean up the data pointed at. It will only clean up the space holding the pointer. If you want the vector to clean up pointer data you need to use some kind of smart pointer implementation:

{     std::vector<SomeClass*> v1;     v1.push_back(new SomeClass());      std::vector<boost::shared_ptr<SomeClass> > v2;     boost::shared_ptr<SomeClass> obj(new SomeClass);     v2.push_back(obj); } 

When that scope ends both vectors will free their internal arrays. v1 will leak the SomeClass that was created since only the pointer to it is in the array. v2 will not leak any data.