Usage sizeof operator

Defined in header <stdatomic.h>

An identifier is an arbitrarily long sequence of digits, underscores, lowercase and uppercase Latin letters, and Unicode characters

Defined in header <wchar.h>

Defined in header <stdlib.h>

Defined in header <stdio.h>

Defined in header <stddef.h>

Defined in header <threads.h>

Defined in header <ctype.h>

Defined in header <stdio.h>