Defined in header <time.h>

Defined in header <stdatomic.h>

Defined in header <wchar.h>

Defined in header <complex.h>

Defined in header <complex.h>

Each of the macros defined in <errno.h> expands to an integer constant expression with type int and with a unique positive value. The following

Defined in header <time.h>

A union is a type consisting of a sequence of members whose storage overlaps (as opposed to struct, which is a type consisting of a sequence of members whose storage is allocated

Usage switch statement:

Defined in header <assert.h>