OFFSETOF(3) | Library Functions Manual | OFFSETOF(3) |
offsetof
—
#include <stddef.h>
size_t
offsetof
(type,
member);
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).
struct example { double x; int y; char z; }; size_t x, y, z; x = offsetof(struct example, x); y = offsetof(struct example, y); z = offsetof(struct example, z); (void)printf("%zu %zu %zu\n", x, y, z);
offsetof
() macro conforms to ANSI
X3.159-1989 (“ANSI C89”).
April 1, 2011 | NetBSD 9.2 |