From cppreference.com
template<classT>structis_compound;(since C++11)std::is_compound is a
.
If T is a compound type (that is, array, function, object pointer, function 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_compound_v, the behavior is undefined.
Template parameters
T - a type to check Helper variable template
template<classT>constexprboolis_compound_v=is_compound<T>::value;(since C++17)Inherited from
Member constants
value
[static]
true if T is a compound type, false otherwise
(public static member constant)Member functions
operator bool
converts the object to bool, returns value
(public member function)operator()
(C++14)
returns value
(public member function)Member types
Type Definition value_typebooltypestd::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<classT>structis_compound:std::integral_constant<bool,!std::is_fundamental<T>::value>{};Example
Run this code
#include<type_traits>#include<iostream>static_assert(notstd::is_compound_v<int>);static_assert(std::is_compound_v<int*>);static_assert(std::is_compound_v<int&>);voidf();static_assert(std::is_compound_v<decltype(f)>);static_assert(std::is_compound_v<decltype(&f)>);static_assert(std::is_compound_v<char[100]>);classC{};static_assert(std::is_compound_v<C>);unionU{};static_assert(std::is_compound_v<U>);enumstructE{e};static_assert(std::is_compound_v<E>);static_assert(std::is_compound_v<decltype(E::e)>);structS{inti:8;intj;voidfoo();};static_assert(notstd::is_compound_v<decltype(S::i)>);static_assert(notstd::is_compound_v<decltype(S::j)>);static_assert(std::is_compound_v<decltype(&S::j)>);static_assert(std::is_compound_v<decltype(&S::foo)>);intmain(){std::cout<<"All checks have passed\n";}See also