std::alignment_of

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Defined in header <type_traits>
template< class T >
struct alignment_of;
 （C++11 起）
提供部件恒定value类型T的对齐要求，等于，仿佛由alignof表达式获得。 T如果是一个数组类型，则返回的元素类型的对齐要求.
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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.
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目录

Inherited from std::integral_constant

Member constants

value
[静态的] </ SPAN></div></div>
alignof(typename std::remove_all_extents<T>::type)
（公共静态成员常量）

Member functions

operator std::size_t
转换的对象std::size_t，返回value
Original:
converts the object to std::size_t, returns value
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（公共成员函数）

Member types

类型
Original:
Type
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 Definition
value_type std::size_t
type std::integral_constant<std::size_t, value>

</div>

[编辑] 可能的实现

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

[编辑] 为例

#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

[编辑] 另请参阅

alignof operator queries alignment requirements of a type （C++11 起） [edit]
（C++11）
定义的类型适合用作未初始化的存储类型的给定尺寸
Original:
defines the type suitable for use as uninitialized storage for types of given size
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（类模板） [edit]
（C++11）
适合所有类型的使用未初始化的存储定义的类型
Original:
defines the type suitable for use as uninitialized storage for all given types
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（类模板） [edit]
（C++11）
POD类型的对齐要求大，任何其他标​​量类型
Original:
POD type with alignment requirement as great as any other scalar type
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（的typedef） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/types/alignment_of&oldid=27709”