Accessing members of parent class

This is a discussion on Accessing members of parent class within the C++ Programming forums, part of the General Programming Boards category; If I have two different classes that are both derived from the same parent class, is it possible for one ...

  1. #1
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    Accessing members of parent class

    If I have two different classes that are both derived from the same parent class, is it possible for one class to access the parent members of the other class? Example:

    Code:
    #include <iostream>
    using namespace std;
    
    class Parent
    {
        protected:
            int value;
    };
    
    
    
    class Child_A : public Parent
    {
        public:
            void Foobar(Parent &other) { cout << other.value << endl; }
    };
    
    
    
    class Child_B : public Parent
    {
        
    };
    
    
    
    int main()
    {
        Child_A a;
        Child_B b;
    
        a.Foobar(b);
        return 0;
    }
    This gives me "int Parent::value is protected". Is it possible in another way?

  2. #2
    The superhaterodyne twomers's Avatar
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    >> void Foobar(Parent &other) { cout << other.value << endl; }

    change to:

    Code:
    void Foobar() { cout << value << endl; }
    the protected values are now variables in the Child_A class, Loosly speaking, so there's no need to pass anything into it. Also, Cild_B isnot a parent type, so:

    Code:
    int main()
    {
        Child_A a;
        Child_B b;
    
        a.Foobar(b);
        return 0;
    }
    that won't work, unless b is declared as:

    Code:
    Parent b;
    Last edited by twomers; 06-29-2006 at 10:23 AM.

  3. #3
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    But I want to access Child_B's value from within a method of Child_A (both are derived from Parent)

  4. #4
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    access value public or via public function inside Parent

    public static member

    Kuphryn

  5. #5
    The superhaterodyne twomers's Avatar
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    then use:

    Code:
    class Child_A : public Child_B
    {
    };
    i guess, or use a public getter in Child_B to get Child_A's variables.

  6. #6
    Registered User whiteflags's Avatar
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    Pass in a const reference to Child_B and access the value.

  7. #7
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    You cannot do what you are trying to do. Child_A has the same access to Child_B's data as any other class that isn't related. You have to provide public accessor methods that anybody can use, or make Child_A a friend of Parent or pass a Child_B and make Child_A a friend of Child_B.

  8. #8
    Super Moderator VirtualAce's Avatar
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    Bad design in any case.

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