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max_align_t

From cppreference.com
< c‎ | types
 
C
 
Type support
 
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.

Contents

[edit] 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.

[edit] 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

[edit] References

  • C23 standard (ISO/IEC 9899:2024):
  • 7.19 Common definitions <stddef.h> (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.19 Common definitions <stddef.h> (p: 211)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.19 Common definitions <stddef.h> (p: 288)

[edit] See also

C++ documentation for max_align_t
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