std::alignment_of

From cppreference.com

Defined in header `<type_traits>`

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

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 [static]	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] Possible implementation

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

[edit] Example

run this code

#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 operator	queries alignment requirements of a type (since C++11)

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)

Language
Standard library headers
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)