std::is_scalar

 

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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
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is_move_constructibleis_trivially_move_constructibleis_nothrow_move_constructible (C++11)(C++11)(C++11)
is_assignableis_trivially_assignableis_nothrow_assignable (C++11)(C++11)(C++11)
is_copy_assignableis_trivially_copy_assignableis_nothrow_copy_assignable (C++11)(C++11)(C++11)
is_move_assignableis_trivially_move_assignableis_nothrow_move_assignable (C++11)(C++11)(C++11)
is_destructibleis_trivially_destructibleis_nothrow_destructible (C++11)(C++11)(C++11)
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Defined in header <type_traits>
template< class T > struct is_scalar;		(since C++11)

If T is a scalar type (that is a possibly cv-qualified arithmetic, pointer, pointer to member, enumeration, or std::nullptr_t type), provides the member constant value equal true. For any other type, value is false.

Template parameters

T

-

a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants

value [static]

true if T is a scalar 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

Each individual memory location in the C++ memory model, including the hidden memory locations used by language features (e.g virtual table pointer), has scalar type (or is a sequence of adjacent bit-fields of non-zero length). Sequencing of side-effects in expression evaluation, interthread synchronization, and dependency ordering are all defined in terms of individual scalar objects.

Possible implementation

template< class T > struct is_scalar : std::integral_constant<bool, std::is_arithmetic<T>::value || std::is_enum<T>::value || std::is_pointer<T>::value || std::is_member_pointer<T>::value || std::is_null_pointer<T>::value> {};

Example

Run this code

#include <iostream>
#include <type_traits>
 
int main() {
    class cls {};
    std::cout << (std::is_scalar<int>::value
                     ? "T is a scalar"
                     : "T is not a scalar") << '\n';
    std::cout << (std::is_scalar<cls>::value
                     ? "T is a scalar"
                     : "T is not a scalar") << '\n';
}

Output:

T is a scalar
T is not a scalar

See also

is_arithmetic (C++11)	checks if a type is an arithmetic type (class template)
is_enum (C++11)	checks if a type is an enumeration type (class template)
is_pointer (C++11)	checks if a type is a pointer type (class template)
is_member_pointer (C++11)	checks if a type is a pointer to an non-static member function or object (class template)