Defined in header <errno.h>

Defined in header <stdio.h>

Defined in header <string.h>

Defined in header <math.h>

If the macro constant __STDC_NO_ATOMICS__(C11) is defined by the compiler, the header <stdatomic.h>

Syntax _Atomic ( type-name )

Defined in header <complex.h>

Defined in header <math.h>

Defined in header <math.h>

Defined in header <threads.h>