The <stddef.h> include file declares the commonly used pointers, variables, and types as listed below:
The <stddef.h> include file also defines the macros NULL and offsetof. NULL is a pointer that is guaranteed not to point to a data object. The offsetof macro expands to the number of bytes between a structure member and the start of the structure. The offsetof macro has the form:
offsetof(structure_type, member)
The <stddef.h> include file also declares the extern variable _EXCP_MSGID, an iSeries extension to C.
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