When a class is instantiated, it is stored in memory and one can call a member function after that. The pointer 'this' refers the calling object inside the member function.
A pointer points to an address and when the pointed address is a function's starting location, we call it as Function Pointer.
Structure and Union are user-defined data types in C and C++. But, they behave differently in C and C++. In this article, you can learn the difference between Structure and Union and its behavior in C and C++.