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dynamic 2d-array

This is a discussion on dynamic 2d-array within the C++ Programming forums, part of the General Programming Boards category; Hi All, While running the below code i am getting Error like :- In member function ‘void Matrix::get_element(int, int, int)’: ...

  1. #1
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    Jun 2012
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    dynamic 2d-array

    Hi All,

    While running the below code i am getting
    Error like :-

    In member function ‘void Matrix::get_element(int, int, int)’:
    cons_2d_array.cpp:13:9: error: invalid types ‘int[int]’ for array subscript
    cons_2d_array.cpp: In member function ‘int& Matrix: put_element(int, int)’:
    cons_2d_array.cpp:16:23: error: invalid types ‘int[int]’ for array subscript
    cons_2d_array.cpp: In constructor ‘Matrix::Matrix(int, int)’:
    cons_2d_array.cpp:23:18: error: cannot convert ‘int**’ to ‘int*’ in assignment
    cons_2d_array.cpp:25:28: error: invalid conversion from ‘int*’ to ‘int’ [-fpermissive]

    Code:
    
    class Matrix
    {
            int *p;
            int d1,d2;
        public:
            Matrix()
            {d1=0;d2=0;}
            Matrix(int x,int y);
    
    
            void get_element(int i, int j, int value)
            {p[i][j]=value;}
    
    
            int & put_element(int i, int j)
            {return p[i][j];}
    };
    
    
    Matrix :: Matrix(const int x, const int y)
    {
            d1=x;
            d2=y;
            p = new int *[d1];
            for(int i=0; i<d1; i++)
               p[i]= new int[d2];
    }

  2. #2
    C++ Witch laserlight's Avatar
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    Stop. Have you considered the use of a std::vector instead of manual memory management of a dynamic array?
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  3. #3
    Captain Crash brewbuck's Avatar
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    So, if I want to get the value of an element, I use put_element(), and if I want to set the value I use get_element()?
    laserlight likes this.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  4. #4
    and the hat of wrongness Salem's Avatar
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    Assuming this is some exercise (use vectors as laserlight says, if this is real code), your member variable needs to be

    Code:
            int **p;
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  5. #5
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    Thanks for advice.
    I am doing R&D with c++ that's why i asked this question.
    Please help me to solve this

  6. #6
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    Thanks,
    I was really missing this part int **p

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