Basic Doubt in Virtual Classes

This is a discussion on Basic Doubt in Virtual Classes within the C++ Programming forums, part of the General Programming Boards category; Code: class Base { public : int a; }; class D1 : virtual public Base { public: int b; }; ...

  1. #1
    Aspiring "Software Guy"
    Join Date
    Aug 2005
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    Basic Doubt in Virtual Classes

    Code:
    class Base
    {
    public :
    int a;
    };
    
    class D1 : virtual public Base
    {
    public:
    int b;
    };
    
    class D2 : virtual public Base
    {
    public:
    int c;
    void change_a()
    {
    a=5;
    }
    };

    D2 makes a=5.
    What effect does this have on the versions of "a" in Base and D1?
    How is memory allocated actually in this program...
    ?

  2. #2
    Registered User
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    In this setup D1 is unrelated to D2, so changing a in an instance of D2 will have no effect on anything that is a D1. Did you mean to add a third class that inherits from both D1 and D2?

  3. #3
    Aspiring "Software Guy"
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    Aug 2005
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    Yes! How did you know? Is it a typical example? or is there some other reason?
    What will be the situation then?

  4. #4
    Deathray Engineer MacGyver's Avatar
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  5. #5
    Registered User
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    >> How did you know?
    Because a virtual base class doesn't make sense unless you are using multiple inheritance.

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