pointer to an instance of a different class

This is a discussion on pointer to an instance of a different class within the C++ Programming forums, part of the General Programming Boards category; This is what I have in hand as of now: class classA { public: int classtype; int dummy; void * ...

  1. #1
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    pointer to an instance of a different class

    This is what I have in hand as of now:
    class classA
    {
    public:
    int classtype;
    int dummy;
    void * pObj;
    };

    class classB
    {
    public:
    int classtype;
    int dummy;
    };

    classA iclassA[20];
    classB iclassB[20];


    int main()
    {
    iclassA[0].pObj = (void *) &iclassB[0];
    iclassB[0].dummy=5;
    system("PAUSE");
    return 0;
    }

    Here void * pObj is an attribute of classA that points to an instance of classB namely iclassB[0]. What I would like to know is how I can assign the value of an attribute of the instance iclassB[0] to an attribute of the instance iclassA[0] that holds pObj.

    Shall appreciate all input.

  2. #2
    pronounced 'fib' FillYourBrain's Avatar
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    Posts
    2,297

    Code:
    class classB;
    class classA
       {
       public:
          int classtype;
          int dummy;
          classB * pObj;
       };
    
    class classB
       {
       public:
          int classtype;
          int dummy;
       };
    
    classA iclassA[20];
    classB iclassB[20];
    
    
    int main()
       {
       iclassA[0].pObj = &iclassB[0];
       iclassB[0].dummy=5;
       system("PAUSE");
       return 0;
       }
    is that what you mean?
    "You are stupid! You are stupid! Oh, and don't forget, you are STUPID!" - Dexter

  3. #3
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    Just a new , your post brought up a glaring question to me. In class a you have void * pObj, and in main you typecast a refrence to a classB object to void. What is a pointer to void? Points to nothing? Why don't you use classB * pObj in your classA declaration instead and avoid the typecast? Just a bit confused, then couldn't you just create a pointer in class B say classB * bObj=classA.pObj?

  4. #4
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    FillYourBrain and curlious, thank you for your input!
    What I am still not clear about though is, given that an instance of class now has an attribute in the form of pObj that is of type classB *, how can this be used to assign values of attributes of the instance of classB to other attributes of the the instance of classA. That is, I have declared that iclassB[0].dummy=5. How can i assign the value that is help by this attribute to the "dummy" of iclassA[0] using pObj ??

  5. #5
    Cat
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    iclassA[0].dummy = iclassA[0].pObj->dummy;

    Is that what you want?

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