[OT] #define

[Andrew Edwards via Digitalmars-d-learn]

Sorry if this is a stupid question but it eludes me. In the 
following, what is THING? What is SOME_THING?

    #ifndef THING
    #define THING
    #endif
    #ifndef SOME_THING
    #define SOME_THING THING *
    #endif

Is this equivalent to:

    alias thing = void;
    alias someThing = thing*;

Thanks,
Andrew