std::max_align_t

typedef /*implementation-defined*/ max_align_t;

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

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

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