help in inheritance classes

This is a discussion on help in inheritance classes within the C++ Programming forums, part of the General Programming Boards category; Hi i am creating a project that will be inherited a class point, squere and cube all together i did ...

  1. #1
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    help in inheritance classes

    Hi i am creating a project that will be inherited a class point, squere and cube all together i did all this and it's in the zip file but i wonted to know what i am putting wrong in main and why when i run the project it gives me address of the memory

    I really need help in the main
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  2. #2
    Registered User Codeplug's Avatar
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    File is corrupted.

    gg

  3. #3
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    here is again the file
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  4. #4
    Registered User Codeplug's Avatar
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    Ok, so what do you need help on? It compiles and runs for me. What is working correctly?

    gg

  5. #5
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    Red face

    I know that after you run this program it compiles and it works but my question is why i am getting this in the ouptut

    Squere s(via * pointPtr):0x0012FF64// Her i don't know why iam getting the address of memory

    and aslo its sayis in the output
    perimeter :6.98771e039 // what's wrong with this

    //and i wonted to make sure if this is corret that what's also my question

    thanks
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  6. #6
    Registered User Codeplug's Avatar
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    A pointer is being printed because that is exactly what you are doing, for example:
    Code:
    int n = 5;
    int *p = &n;
    ...
    cout << p << endl;   //prints the address of n
    cout << *p << endl;  //prints "5"
    Your other problem is that you are trying to cast up inheritance that wasn't previously cast down, for example:
    Code:
    class base {};
    class child : public base {};
    ...
    child c;
    base *pb = static_cast<base*>(&c);    //cast down, ok
    child *pc = static_cast<child*>(pb);  //cast back up, ok since pb points to type child
    ...
    base b;
    pb = &b; //pb now points to type base
    pc = static_cast<child*>(pb); //cast up, but pb currently points to type base - this is garbage, results undefined
    Once you undestand that, what is wrong with this?
    Code:
    pointPtr = &p;
    squarePtr = static_cast<Square *>(pointPtr); //cast up!!!!
    gg

  7. #7
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    Thanks a lot Codeplug
    for explaining to me what was going on that code i am not using pointer at all now and it's working perfect
    You are the Best Codeplug
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  8. #8
    Programming Sex-God Polymorphic OOP's Avatar
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    Originally posted by Codeplug

    Code:
    child *pc = static_cast<child*>(pb);  //cast back up, ok since pb points to type child
    when casting up you should use dynamic_cast not static_cast

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