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std::is_null_pointer

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(C++11)
is_null_pointer
(C++14)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
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(C++11)
(C++11)
(C++11)
(C++14)
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(C++11)
(C++11)
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Defined in header <type_traits>
template< class T >
struct is_null_pointer;
(since C++14)

Checks whether T is the type std::nullptr_t.

Provides the member constant value that is equal to true, if T is the type std::nullptr_t, const std::nullptr_t, volatile std::nullptr_t, or const volatile std::nullptr_t.

Otherwise, value is equal to false.

Contents

[edit] Template parameters

T - a type to check

Inherited from std::integral_constant

Member constants

value
[static]
true if T is the type std::nullptr_t (possibly cv-qualified) , 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

std::is_pointer is false for std::nullptr_t because it is not a built-in pointer type.

[edit] Example

#include <iostream>
#include <type_traits>
 
int main()
{
    std::cout << std::boolalpha
              << std::is_null_pointer< decltype(nullptr) >::value << ' '
              << std::is_null_pointer< int* >::value << '\n'
              << std::is_pointer< decltype(nullptr) >::value << ' '
              << std::is_pointer<int*>::value << '\n';
}

Output:

true false
false true

[edit] See also

(C++11)
checks if a type is void
(class template) [edit]
(C++11)
checks if a type is an array type
(class template) [edit]
checks if a type is a pointer type
(class template) [edit]
(C++11)
checks if a type is an enumeration type
(class template) [edit]
(C++11)
checks if a type is an union type
(class template) [edit]
(C++11)
checks if a type is a class type (but not union type)
(class template) [edit]
checks if a type is a function type
(class template) [edit]
(C++11)
checks if a type is object type
(class template) [edit]