Question

I tried the following but it just returns a screwed up array.

    T[,] ResizeArray<T>(T[,] original, int rows, int cols)
    {
        var newArray = new T[rows,cols];
        Array.Copy(original, newArray, original.Length);
        return newArray;
    }

Answer 1

Thank you Thomas, your explanation was very helpful but your implemented solution is too slow. I modified it to put Array.Copy to good use.

    void ResizeArray<T>(ref T[,] original, int newCoNum, int newRoNum)
    {
        var newArray = new T[newCoNum,newRoNum];
        int columnCount = original.GetLength(1);
        int columnCount2 = newRoNum;
        int columns = original.GetUpperBound(0);
        for (int co = 0; co <= columns; co++)
            Array.Copy(original, co * columnCount, newArray, co * columnCount2, columnCount);
        original = newArray;
    }

Here I’m assuming that there are more rows than columns so I structured the array as [columns, rows]. That way I use Array.Copy on an entire column in one shot (much faster than one cell a time).

It only works to increment the size of the array but it can probably be tweaked to reduce the size too.