Defined in header <type_traits> | ||
---|---|---|
template< std::size_t Len, class... Types > struct aligned_union; | (since C++11) |
Provides the member typedef type
, which is a POD type of a size and alignment suitable for use as uninitialized storage for an object of any of the types listed in Types
. The size of the storage is at least Len
. std::aligned_union
also determines the strictest (largest) alignment requirement among all Types
and makes it available as the constant alignment_value
.
If sizeof...(Types) == 0
, the behavior is undefined.
Member types
Name | Definition |
---|---|
type | the POD type suitable for storage of any type from Types |
Helper types
template< std::size_t Len, class... Types > using aligned_union_t = typename aligned_union<Len,Types...>::type; | (since C++14) |
Member constants
alignment_value [static] | the strictest alignment requirement of all Types (public static member constant) |
Possible implementation
#include <algorithm> template <std::size_t Len, class... Types> struct aligned_union { static constexpr std::size_t alignment_value = std::max({alignof(Types)...}); struct type { alignas(alignment_value) char _s[std::max({Len, sizeof(Types)...})]; }; }; |
Example
See also
(C++11) | obtains the type's alignment requirements (class template) |
(C++11) | defines the type suitable for use as uninitialized storage for types of given size (class template) |
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