std::max_align_t

 

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ptrdiff_t size_t max_align_t (C++11)     byte (C++17)	nullptr_t (C++11) offsetof NULL
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Defined in header <cstddef>
typedef /*implementation-defined*/ max_align_t;		(since C++11)

std::max_align_t is a trivial standard-layout type whose alignment requirement is at least as strict (as large) as that of every scalar type.

Notes

Pointers returned by allocation functions such as std::malloc are suitably aligned for any object, which means they are aligned at least as strictly as std::max_align_t.

std::max_align_t is usually synonymous with the largest scalar type, which is long double on most platforms, and its alignment requirement is either 8 or 16.

Example

Run this code

#include <iostream>
#include <cstddef>
int main()
{
    std::cout << alignof(std::max_align_t) << '\n';
}

Possible output:

16

References

• C++23 standard (ISO/IEC 14882:2023):

• 17.2.4 Sizes, alignments, and offsets [support.types.layout] (p: 504-505)

• C++20 standard (ISO/IEC 14882:2020):

• 17.2.4 Sizes, alignments, and offsets [support.types.layout] (p: 507-508)

• C++17 standard (ISO/IEC 14882:2017):

• 21.2.4 Sizes, alignments, and offsets [support.types.layout] (p: 479)

• C++14 standard (ISO/IEC 14882:2014):

• 18.2 Types [support.types] (p: 443-444)

• C++11 standard (ISO/IEC 14882:2011):

• 18.2 Types [support.types] (p: 454-455)

See also

alignof operator(C++11)	queries alignment requirements of a type
alignment_of (C++11)	obtains the type's alignment requirements (class template)
is_scalar (C++11)	checks if a type is a scalar type (class template)