IUnknown

This is a discussion on IUnknown within the C++ Programming forums, part of the General Programming Boards category; Hello everyone, I am reading Unknwn.h, and the code logics is a little fuzzy. The QueryInterface, AddRef an Release are ...

  1. #1
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    IUnknown

    Hello everyone,


    I am reading Unknwn.h, and the code logics is a little fuzzy. The QueryInterface, AddRef an Release are all pure virtual methods, right?


    thanks advance,
    George

  2. #2
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    That's right. IUnknown is part of a framework known as COM. Basically, all interfaces inherit from IUknown which means you can call any of those 3 functions on any interface (or object which inherits from those interfaces).

    AddRef() and Release() are just functions for reference counting. QueryInterface() allows you to find out what interface anything else inherits from at runtime.

    Even though COM was created by Microsoft, a lot of other people use the same principals in their framework. My company does the same thing; we have a common interface with the same 3 virtual functions.

  3. #3
    Cat without Hat CornedBee's Avatar
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    Reading COM header files won't get you anywhere. Read a good COM tutorial instead.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  4. #4
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    Thanks bithub and CornedBee!


    My question is answered.

    Quote Originally Posted by CornedBee View Post
    Reading COM header files won't get you anywhere. Read a good COM tutorial instead.

    regards,
    George

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