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std::is_scalar

From cppreference.com
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is_scalar
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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, arithmetic type, enumeration type, pointer, pointer to member, or std::nullptr_t, including any cv-qualified variants), provides the member constant value equal true. For any other type, value is false.

Contents

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>
[edit template]

[edit] 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.

[edit] 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_same<std::nullptr_t, typename std::remove_cv<T>::type>::value> {};

[edit] Example

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

Output:

T is scalar
T is not a scalar

[edit] See also

checks if a type is arithmetic type
(class template) [edit]
(C++11)
checks if a type is an enumeration type
(class template) [edit]
checks if a type is a pointer type
(class template) [edit]
checks if a type is a pointer to a non-static member function or object
(class template) [edit]