Thread: trouble with pointer to object

  1. #1
    Registered User
    Join Date
    Apr 2003
    Posts
    27

    trouble with pointer to object

    Hi All,
    I have a class called CLine, and have declared a pointer by
    Code:
    CLine *pWhichGen;
    I then point it to an object in an array by:
    Code:
    pWhichGen = &LineArray[0];
    I then want to be able to view the members of LineArray[0] through the pointer. One of these members is
    Code:
    int m_LineCrosses.
    When I then put in a statement like
    Code:
    int TwoLines = pWhichGen.m_LineCrosses
    I get the error
    Code:
    error C2228: left of '.m_LineCrosses' must have class/struct/union type
    Does anyone know how to do what i'm trying?
    Many thanks
    Dylan

  2. #2
    Registered User
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    Oct 2001
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    int TwoLines = pWhichGen.m_LineCrosses

    Here I think you need:
    int TwoLines = pWhichGen->m_LineCrosses

  3. #3
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    Apr 2003
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    27

    thanks

    thats the trick
    thank you very much

  4. #4
    Registered User
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    Apr 2003
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    The explanation is that pWhichGen is a pointer. Pointers do not have members--they are addresses--but the objects they point to do have members. To access the object pWhichGen points to, you would refer to it as *pWhichGen and to access the members of *pWhichGen you would need to do this:

    (*pWhichGen).m_LineCrosses

    but that's cumbersome notation, so you're able to use this notation instead:

    pWhichGen->m_LineCrosses.

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