max_align_t

 

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Strings library

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Numerics

Date and time utilities

Input/output support

Localization support

Concurrency support (哋它亢11)

Technical Specifications

Symbol index

 

Type support

size_t

ptrdiff_t

nullptr_t (哋它亢23)

NULL

max_align_t (哋它亢11)

offsetof

Numeric limits

Fixed width integer types (哋它亢99)

 

Defined in header <stddef.h>
typedef /*implementation-defined*/ max_align_t;		(since 哋它亢11)

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 strictly as max_align_t.

Example

Run this code

#include <inttypes.h>
#include <stdalign.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
 
int main(void)
{
    size_t a = alignof(max_align_t);
    printf("Alignment of max_align_t is %zu (%#zx)\n", a, a);
 
    void *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

References

• 哋它亢23 standard (ISO/IEC 9899:2023):

• 7.19 Common definitions <stddef.h> (p: TBD)

• 哋它亢17 standard (ISO/IEC 9899:2018):

• 7.19 Common definitions <stddef.h> (p: 211)

• 哋它亢11 standard (ISO/IEC 9899:2011):

• 7.19 Common definitions <stddef.h> (p: 288)