std::alignment_of

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Defined in header `<type_traits>`

template< class T > struct alignment_of;		(C++11 feature)

Provides the member constant value equal to the alignment requirement of the type T, as if obtained by an alignof expression. If T is an array type, returns the alignment requirements of the element type.

Inherited from std::integral_constant

Member constants


`value`	alignof(typename std::remove_all_extents<T>::type) (public static member constant)

Member functions


`operator std::size_t`	converts the object to std::size_t, returns `value` (public member function)

Member types


Type	Definition

`value_type`	`std::size_t`

`type`	std::integral_constant<std::size_t, value>

[edit] Equivalent definition

template< class T >
struct alignment_of : std::integral_constant<
                          std::size_t,
                          alignof(typename std::remove_all_extents<T>::type)
                       > {};

[edit] Example

#include <iostream>
#include <type_traits>
 
class A {};
 
int main() 
{
    std::cout << std::alignment_of<A>::value << '\n';
    std::cout << std::alignment_of<int>::value << '\n';
    std::cout << std::alignment_of<double>::value << '\n';
}

Output:

1
4
8

[edit] See also

alignof

(keyword)

aligned_storage (C++11)

defines the type suitable for use as uninitialized storage for types of given size
(class template)

aligned_union (C++11)

defines the type suitable for use as uninitialized storage for all given types
(class template)

max_align_t (C++11)

POD type with alignment requirement as great as any other scalar type
(typedef)