Re: Converting an array to a multidimensional one

Maxim Yegorushkin <>
Wed, 19 Nov 2008 01:12:12 -0800 (PST)
On Nov 19, 2:14 am, Slain <> wrote:

I need to convert a an array to a multidimensional one. Since I need
to wrok with existing code, I need to modify a declaration which looks
like this

In the .h file
int *x;

No need to modify the declaration. Multidimensional arrays in C++ are
stored as one-dimensional arrays anyway.

What you need to modify is how you calculate one-dimensional index.

in a initialize function:
x = new int[$Row_Length];

$Row_Length - is that a shell or Perl variable in here? ;)

Now I need the x to be able to point to a multidimensional array
I would ahve been fine, with something like
int (*x)[Column_Length] = new int [Row_Length][Column_Length];

But since my variable x needs to be declated in the header file, I am
having some problems compiling. Can some one explain me how to declare
and initialize?

You allocate your two-dimensional array like this:

    int* x = new int[Row_Length * Column_Length];

And index into it like this:

    int row, col; // initialised elsewhere
    // access an element at x[row][col]
    int& elem = x[row * Column_Length + col];


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