Retrieves the offset of a member from the beginning of its parent structure.
Name of the parent data structure.
Name of the member in the parent data structure for which to determine the offset.
offsetof returns the offset in bytes of the specified member from the beginning of its parent data structure. It is undefined for bit fields.
The offsetof macro returns the offset in bytes of memberName from the beginning of the structure specified by structName as a value of type size_t. You can specify types with the struct keyword.
offsetof is not a function and cannot be described using a C prototype.
For additional compatibility information, see Compatibility in the Introduction.