max_align_t

 

C

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headers

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Technical Specifications

 

Type support

size_t

ptrdiff_t

NULL

max_align_t (since C11)

offsetof

Numeric limits

 

Defined in header <stddef.h>
typedef /*implementation-defined*/ max_align_t;		(since C11)

max_align_t is a 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 malloc are suitably aligned for any object, which means they are aligned at least as strict as max_align_t.

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 <stdio.h>
#include <stddef.h>
#include <stdalign.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
 
int main(void)
{
    size_t a = alignof(max_align_t);
    printf("Alignment of max_align_t is %zu (%#zx)\n", a, a);
 
    int *p = malloc(123);
    printf("The address obtained from malloc(123) is %#" PRIxPTR"\n",
            (uintptr_t)p);
    free(p);
}

Possible output:

Alignment of max_align_t is 16 (0x10)
The address obtained from malloc(123) is 0x1fa67010

See also

C++ documentation for max_align_t