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    std::alignment_of

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    Defined in header <type_traits>
    template< class T > struct alignment_of;
    		 (since C++11)
    See More

    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. If T is a reference type, returns the alignment requirements of the type referred to.

    If alignof(T) is not a valid expression, the behavior is undefined.

    If the program adds specializations for std::alignment_of or std::alignment_of_v(since C++17), the behavior is undefined.

    Helper variable template

    template< class T > constexpr std::size_t alignment_of_v = alignment_of<T>::value;
    		 (since C++17)

    Inherited from std::integral_constant

    Member constants

    value
    [static]
    		 alignof(T)
    (public static member constant)

    Member functions

    operator std::size_t
    		 converts the object to std::size_t, returns value
    (public member function)
    operator()
    (C++14)
    		 returns value
    (public member function)

    Member types

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

    Possible implementation

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

    Notes

    This type trait predates the alignof keyword, which can be used to obtain the same value with less verbosity.

    Example

    Run this code
    #include <cstdint>
#include <iostream>
#include <type_traits>

struct A {};
struct B
{
    std::int8_t p;
    std::int16_t q;
};

int main()
{
    std::cout << std::alignment_of<A>::value << ' ';
    std::cout << std::alignment_of<B>::value << ' ';
    std::cout << std::alignment_of<int>() << ' '; // alt syntax
    std::cout << std::alignment_of_v<double> << '\n'; // c++17 alt syntax
}

    Possible output: 

    1 2 4 8

    See also

    alignof (C++11) queries alignment requirements of a type
    (operator)[edit]
    alignas (C++11) specifies that the storage for the variable should be aligned by specific amount
    (specifier)[edit]
    (since C++11)(deprecated in C++23)
    		 defines the type suitable for use as uninitialized storage for types of given size
    (class template) [edit]
    (since C++11)(deprecated in C++23)
    		 defines the type suitable for use as uninitialized storage for all given types
    (class template) [edit]
    (C++11)
    		 trivial type with alignment requirement as great as any other scalar type
    (typedef) [edit]