std::is_object

C++ Reference
Language Concepts Utilities library Strings library Containers library Algorithms library Iterators library Numerics library Input/output library Localizations library Regular expressions library (C++11) Atomic operations library (C++11) Thread support library (C++11)
Utilities library
Type support
Basic types Fundamental types Fixed width integer types (C++11) ptrdiff_t size_t max_align_t (C++11) nullptr_t (C++11) offsetof NULL Numeric limits numeric_limits C numeric limits interface Runtime type information type_info type_index (C++11) bad_typeid bad_cast Type traits Primary type categories is_void (C++11) is_array (C++11) is_pointer (C++11) is_enum (C++11) is_union (C++11) is_class (C++11) is_function (C++11) is_object (C++11) is_scalar (C++11) is_compound (C++11) is_integral (C++11) is_floating_point (C++11) is_fundamental (C++11) is_arithmetic (C++11) is_reference (C++11) is_lvalue_reference (C++11) is_rvalue_reference (C++11) is_member_pointer (C++11) is_member_object_pointer (C++11) is_member_function_pointer (C++11) Type properties is_const (C++11) is_volatile (C++11) is_pod (C++11) is_empty (C++11) is_polymorphic (C++11) is_abstract (C++11) is_trivial (C++11) is_trivially_copyable (C++11) is_standard_layout (C++11) is_literal_type (C++11) is_signed (C++11) is_unsigned (C++11) Supported operations is_constructible is_trivially_constructible is_nothrow_constructible (C++11) (C++11) (C++11) is_default_constructible is_trivially_default_constructible is_nothrow_default_constructible (C++11) (C++11) (C++11) is_copy_constructible is_trivially_copy_constructible is_nothrow_copy_constructible (C++11) (C++11) (C++11) is_move_constructible is_trivially_move_constructible is_nothrow_move_constructible (C++11) (C++11) (C++11) is_assignable is_trivially_assignable is_nothrow_assignable (C++11) (C++11) (C++11) is_copy_assignable is_trivially_copy_assignable is_nothrow_copy_assignable (C++11) (C++11) (C++11) is_move_assignable is_trivially_move_assignable is_nothrow_move_assignable (C++11) (C++11) (C++11) is_destructible is_trivially_destructible is_nothrow_destructible (C++11) (C++11) (C++11) has_virtual_destructor (C++11) Relationships and property queries is_same (C++11) is_base_of (C++11) is_convertible (C++11) alignment_of (C++11) rank (C++11) extent (C++11) Type modifications remove_cv remove_const remove_volatile (C++11) (C++11) (C++11) add_cv add_const add_volatile (C++11) (C++11) (C++11) make_signed (C++11) make_unsigned (C++11) remove_reference (C++11) add_lvalue_reference add_rvalue_reference (C++11) (C++11) remove_pointer (C++11) add_pointer (C++11) remove_extent (C++11) remove_all_extents (C++11) Type transformations aligned_storage (C++11) aligned_union (C++11) decay (C++11) enable_if (C++11) conditional (C++11) common_type (C++11) underlying_type (C++11) result_of (C++11) Type trait constants integral_constant (C++11)

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

If T is an object type (that is, scalar, array, class, or union), provides the member constant value equal true. For any other type, value is false.

Inherited from std::integral_constant

Member constants

value [static]	true if T is an object type , false otherwise (public static member constant)

Member functions

operator bool	converts the object to bool, returns value (public member function)

Member types

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

Possible implementation

template< class T> struct is_object : std::integral_constant<bool, std::is_scalar<T>::value || std::is_array<T>::value || std::is_union<T>::value || std::is_class<T>::value> {};

Example

#include <iostream>
#include <type_traits>
 
int main() {
    class cls {};
    std::cout << std::boolalpha;
    std::cout << std::is_object<int>::value << '\n';
    std::cout << std::is_object<int&>::value << '\n';
    std::cout << std::is_object<cls>::value << '\n';
    std::cout << std::is_object<cls&>::value << '\n';
}

Output:

true
false
true
false

See also

is_scalar (C++11)	checks if a type is scalar type (class template)
is_array (C++11)	checks if a type is an array type (class template)
is_union (C++11)	checks if a type is an union type (class template)
is_class (C++11)	checks if a type is a class type (but not union type) (class template)