Thank you for the reply.

This is just a testing program for this question. What you said is that even the destructor is called for ClassA, and TestClass is out off scope in main function, the memory for ClassA may still be around and valid on the main thread's stack. I think I have to agree with you that this is depended on the compiler. According to C++ standard, "the object no longer exists" once a destructor is invoked for an object. It depends on how do we understand this "no longer exists".

From the C++ standard : (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2723.pdf)
Once a destructor is invoked for an object, the object no longer exists; the behavior is undefined if the destructor is invoked for an object whose lifetime has ended.