Can a object be passed as value to the copy constructor

Question

I have some confusion with this \"Can a object be passed as value to the copy constructor\" The compiler clearly rejects this, which means it is not possible. Can you help m

Answer 1

The standard specifically says (12.1/10 Constructors):

A copy constructor for a class X is a constructor with a first parameter of type X& or of type const X&

So it can't take a value parameter - it must be a reference.

If you think about if for a moment, it should be clear why: to pass a value parameter, the compiler must make a copy... It needs to invoke the copy constructor to do so.