Is a union in C++ actually a class?

Question

A junior developer asked me if it was possible to overload assignment operators for a union with POD arguments such that the corresponding data type within the union would g

Answer 1

Is a union in C++ actually a class?

Yes. In C++ a union is a class: a special kind of class.

C++11: 9 Classes (p5):

A union is a class defined with the class-key union; it holds only one data member at a time

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Is it actually common to overload constructors etc for unions in this way?

A union is a special class with some restrictions:

9.5 Unions (p2):

A union can have member functions (including constructors and destructors), but not virtual (10.3) functions. A union shall not have base classes. A union shall not be used as a base class.

11 Member access control (p3):

Members of a class defined with the keyword class are private by default. Members of a class defined with the keywords struct or unionare public by default.

So, you can overload constructors, destructors and operators similar to as you can do in a class.