On 2005-02-02, Eljay Love-Jensen <eljay@xxxxxxxxx> wrote: > > Yes, it's ok -- for a lot of operations. What you are dealing with is a > pointer. A pointer is a fundamental data type. > Can "pointer", by itself, be considered a data-type? I always though that the data-type was actually "pointer to something", which is a different type from "pointer to something-else"? > What you cannot do is increment/decrement the pointer, use array access, or > access the (undefined, unknown) members, or dereference the pointer in any > other fashion[1]. So in my original example, if I added something like "foo.b++", it would fail. The error message is: error: increment of pointer to unknown structure error: arithmetic on pointer to an incomplete type Which indicates that "struct bar" is indeed a defined, but incomplete, data-type, and that it is ok to define pointers to incomplete data-types. Such pointers (i.e. pointer to incomplete data-types) have "special" semantics (similar but not identical to those of "void" pointers). Thanks for helping me sort this out. /npat
