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std::is_compound(3)	       C++ Standard Libary	     std::is_compound(3)

NAME
     std::is_compound - std::is_compound

Synopsis
	Defined in header <type_traits>
	template< class T >		 (since C++11)
	struct is_compound;

	std::is_compound is a UnaryTypeTrait.

	If T is a compound type (that is, array, function, object pointer, func-
     tion pointer,
	member object pointer, member function pointer, reference, class, union,
     or
	enumeration,  including  any cv-qualified variants), provides the member
     constant
	value equal true. For any other type, value is false.

	If the program adds specializations for std::is_compound or std::is_com-
     pound_v, the
	behavior is undefined.

Template parameters
	T - a type to check

	Helper variable template

	template<  class  T  >						  (since
     C++17)
	inline constexpr bool is_compound_v = is_compound<T>::value;

     Inherited from std::integral_constant

Member constants
	value	 true if T is a compound type, false otherwise
	[static] (public static member constant)

Member functions
	operator bool converts the object to bool, returns value
		      (public member function)
	operator()    returns value
	(C++14)       (public member function)

Member types
	Type	   Definition
	value_type bool
	type	   std::integral_constant<bool, value>

Notes
	Compound  types  are  the  types  that	are constructed from fundamental
     types. Any C++
	type is either fundamental or compound.

Possible implementation
	template<class T>
	struct	is_compound  :	std::integral_constant<bool,  !std::is_fundamen-
     tal<T>::value> {};

Example
     // Run this code

      #include <type_traits>
      #include <iostream>

      static_assert(not std::is_compound_v<int>);
      static_assert(std::is_compound_v<int*>);
      static_assert(std::is_compound_v<int&>);

      void f();
      static_assert(std::is_compound_v<decltype(f)>);
      static_assert(std::is_compound_v<decltype(&f)>);

      static_assert(std::is_compound_v<char[100]>);

      class C {};
      static_assert(std::is_compound_v<C>);

      union U {};
      static_assert(std::is_compound_v<U>);

      enum struct E { e };
      static_assert(std::is_compound_v<E>);
      static_assert(std::is_compound_v<decltype(E::e)>);

      struct S
      {
	  int i : 8;
	  int j;
	  void foo();
      };
      static_assert(not std::is_compound_v<decltype(S::i)>);
      static_assert(not std::is_compound_v<decltype(S::j)>);
      static_assert(std::is_compound_v<decltype(&S::j)>);
      static_assert(std::is_compound_v<decltype(&S::foo)>);

      int main()
      {
	  std::cout << "All checks have passed\n";
      }

See also
	is_fundamental checks if a type is a fundamental type
	(C++11)        (class template)
	is_scalar      checks if a type is a scalar type
	(C++11)        (class template)
	is_object      checks if a type is an object type
	(C++11)        (class template)
	is_array       checks if a type is an array type
	(C++11)        (class template)

http://cppreference.com 	   2024.06.10		     std::is_compound(3)
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