Why is an array called a derived data type?

Answer 1

An array is not a derived data type at all. In order to be derived there has to be a base class and an array has no base class. Here is the basic declaration of the std::array template class from the <array> header file:

template<class _Ty, size_t _Size>

class array

{ // fixed size array of values

// ...

};

A vector, on the other hand, is derived (from the <vector> header file):

template<class _Ty, class _Alloc = allocator<_Ty>>

class vector : public _Vector_alloc<!is_empty<_Alloc>::value, _Vec_base_types<_Ty, _Alloc>>

{ // varying size array of values

// ...

};