std::is_compound

 

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

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.

The behavior of a program that adds specializations for is_compound or is_compound_v (since C++17) is undefined.

Template parameters

T

-

a type to check

Helper variable template

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

Inherited from std::integral_constant

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_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_fundamental<T>::value> {};

Example

Run this code

#include <iostream>
#include <type_traits>
 
int main() {
    class cls {};
    std::cout << (std::is_compound<cls>::value
                     ? "`cls` is compound"
                     : "`cls` is not a compound") << '\n';
    std::cout << (std::is_compound_v<int>
                     ? "`int` is compound"
                     : "`int` is not a compound") << '\n';
}

Output:

`cls` is compound
`int` is not a compound

See also

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