C Language _Alignof



Queries the alignment requirement for the specified type. The alignment requirement is a positive integral power of 2 representing the number of bytes between which two objects of the type may be allocated. In C, the alignment requirement is measured in size_t.

The type name may not be an incomplete type nor a function type. If an array is used as the type, the type of the array element is used.

This operator is often accessed through the convenience macro alignof from <stdalign.h>.

int main(void)
    printf("Alignment of char = %zu\n", alignof(char));
    printf("Alignment of max_align_t = %zu\n", alignof(max_align_t));
    printf("alignof(float[10]) = %zu\n", alignof(float[10]));
    printf("alignof(struct{char c; int n;}) = %zu\n",
            alignof(struct {char c; int n;}));    

Possible Output:

Alignment of char = 1
Alignment of max_align_t = 16
alignof(float[10]) = 4
alignof(struct{char c; int n;}) = 4