ptrdiff_t

This is the signed integral type and is the result of subtracting two pointers.

size_t

This is the unsigned integral type and is the result of the sizeof keyword.

wchar_t

This is an integral type of the size of a wide character constant.

This macro is the value of a null pointer constant.

This results in a constant integer of type size_t which is the offset in bytes of a structure member from the beginning of the structure. The member is given by member-designator, and the name of the structure is given in type.