Size of a Empty Class with Virtual Function?

What is the size of the below class?

struct MyClass
{
    virtual ~MyClass();
};

The answer is size of a pointer(4 bytes or 8 bytes depending on the platform). That pointer is a vptr to vtbl of virtual functions. That being said, it is not a good idea to initialize a class consisting of POD members but with virtual functions by zeroing its memory with memset() because its vptr ended up overwritten.