1.\" 2.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org> 3.\" 4.\" SPDX-License-Identifier: BSD-2-Clause 5.\" 6.Dd November 10, 2025 7.Dt MEMALIGNMENT 3 8.Os 9.Sh NAME 10.Nm memalignment 11.Nd find the memory alignment of an object 12.Sh SYNOPSIS 13.Lb libc 14.In stdlib.h 15.Ft size_t 16.Fn memalignment "const void *ptr" 17.Sh DESCRIPTION 18The 19.Fn memalignment 20function determines the alignment of the object pointed to by 21.Fa ptr . 22This alignment is a power of\~2, and may be larger than the range 23supported by the 24.Sy alignof 25operator. 26The value returned can be compared to the result of 27.Sy alignof , 28and if it is greater or equal, the alignment requirement of the operand 29is satisfied. 30.Sh RETURN VALUES 31Returns the alignment of 32.Fa ptr 33as a power of\~2. 34If 35.Fa ptr 36is a null pointer, an alignment of zero is returned. 37An alignment of zero indicates that the tested pointer cannot be used to 38access an object of any type. 39.Sh SEE ALSO 40.Xr aligned_alloc 3 , 41.Xr posix_memalign 3 42.Sh STANDARDS 43The 44.Fn memalignment 45function conforms to 46.St -isoC-2023 . 47.Sh HISTORY 48The 49.Fn memalignment 50function was added in 51.Fx 15.1. 52.Sh AUTHOR 53.An Robert Clausecker Aq Mt fuz@FreeBSD.org 54