C <stddef.h> - max_align_t Type

The C <stddef.h> max_align_t is a type whose alignment requirement is at strict (as large) as that of any possible scalar type, and whose alignment requirement is supported in every context.

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.

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.

In the <stddef.h> header file, it is defined as follows:

• C11

typedef /* implementation-defined */ max_align_t;

Example:

In the example below shows how to get the alignment requirement of a given platform.

#include <stdio.h>
#include <stddef.h>
#include <stdalign.h>
 
int main() {
  size_t x = alignof(max_align_t);
  printf("Alignment of max_align_t is: %zu", x);
  
  return 0;
}

The output of the above code will be:

Alignment of max_align_t is: 16