Manual Pages  — OFFSETOF

offsetof – offset of a structure member

SYNOPSIS DESCRIPTION STANDARDS

#include <stddef.h>

size_t
offsetof(type, member);

The offsetof() macro expands to an integer constant expression of type size_t and yields the offset, in bytes, of the field member from the start of the structure type.

A compiler error will result if member is not aligned to a byte boundary (i.e. it is a bit-field).

The offsetof() macro conforms to -ansiC.