How to point correctly?

This is a discussion on How to point correctly? within the C++ Programming forums, part of the General Programming Boards category; How do I make ptr_1 pointing to the same address of ptr_2 after function_B is called? I tried doing this, ...

  1. #1
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    How to point correctly?

    How do I make ptr_1 pointing to the same address of ptr_2 after function_B is called? I tried doing this, but after function_B exits, ptr_1 points back to NULL. Thanks!

    Code:
    void cluster::function_A(void)
    {
    	int *ptr_1, *ptr_2;
    	ptr_1 = NULL;
    	ptr_2 = new int [ 10 ];
    	function_B(ptr_1, ptr_2);
    
    }
    
    void cluster::function_B(int *ptr_1, int *ptr_2)
    {
    	ptr_1 = ptr_2;
    }

  2. #2
    C++ Witch laserlight's Avatar
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    Pass ptr_1 by reference.
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    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
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    ok, i get it, i do this right?

    Code:
    void cluster::function_B(int *&ptr_1, int *&ptr_2)
    {
    	ptr_1 = ptr_2;
    }

  4. #4
    C++ Witch laserlight's Avatar
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    Yes, though in this example you do not need to pass ptr_2 by reference as it is not modified. Of course, this example is so simple that one would just write the assignment instead of calling the function
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  5. #5
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    ok, thanks a lot for guiding me, i found an excellent article on this issue =)

    http://www.codeproject.com/cpp/PtrToPtr.asp

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