What are destructors in c plus plus?

Answer 1

A destructor in C++ is a method of a class that runs when the class is deleted. It performs cleanup of the members of the class that need cleanup, such as deallocation of subobjects referred to by pointers in the class, subobjects which were earlier allocated by a constructor or other method of the class.

Answer 2

Yes, although there are few practical reasons for doing so. The primary reason is to ensure only one instance of a class exists at all times (a singleton class). However, you must still provide some means of destroying the singleton, typically achieved via a static member function or a friend class or function.

Answer 3

No -- it would make no sense to have a static destructor. Static members are local to the class. You cannot destroy a class, only an instance of a class, an object. Objects have no static members.