Does Array.Copy work with multidimensional arrays?

Question

This code works fine:

var newArray = new Rectangle[newHeight, newWidth];

for (int x = 0; x < newWidth; x++)
    for (int y = 0; y < newHeight; y++)
           


        

Answer 1

I use this code:

public static void ResizeBidimArrayWithElements<T>(ref T[,] original, int rows, int cols)
{

    T[,] newArray = new T[rows, cols];
    int minX = Math.Min(original.GetLength(0), newArray.GetLength(0));
    int minY = Math.Min(original.GetLength(1), newArray.GetLength(1));

    for (int i = 0; i < minX; ++i)
        Array.Copy(original, i * original.GetLength(1), newArray, i * newArray.GetLength(1), minY);

    original = newArray;

}

calling like this for array of strings

ResizeBidimArrayWithElements<string>(ref arrayOrigin, vNumRows, vNumCols);

Answer 2

I had a need to consume data from a buffer and copy off to a large holding array before the next interrupt hit. Copying in a loop wasn't an option; far too slow. I didn't need the multidimensional structure of the combined data until all of the copying was done, this meant I could Buffer.BlockCopy() to a single dimension array, then copy again onto a multidimensional array to obtain the required structure. Here's some code (run it in a console) that will demonstrate the technique as well as the performance.

static class Program
{
    [STAThread]
    static void Main()
    {
        Stopwatch watch = new Stopwatch();

        const int width = 2;
        const int depth = 10 * 1000000;

        //  Create a large array of data
        Random r = new Random(100);
        int[,] data = new int[width, depth];
        for(int i = 0; i < width; i++)
        {
            for(int j = 0; j < depth; j++)
            {
                data[i, j] = r.Next();
            }
        }

        //  Block copy to a single dimension array
        watch.Start();
        int[] buffer = new int[width * depth];
        Buffer.BlockCopy(data, 0, buffer, 0, data.Length * sizeof(int));
        watch.Stop();
        Console.WriteLine("BlockCopy to flat array took {0}", watch.ElapsedMilliseconds);

        //  Block copy to multidimensional array
        int[,] data2 = new int[width, depth];
        watch.Start();
        Buffer.BlockCopy(buffer, 0, data2, 0,buffer.Length * sizeof(int));
        watch.Stop();
        Console.WriteLine("BlockCopy to 2 dimensional array took {0}", watch.ElapsedMilliseconds);


        //  Now try a loop based copy - eck!
        data2 = new int[width, depth];
        watch.Start();
        for (int i = 0; i < width; i++)
        {
            for (int j = 0; j < depth; j++)
            {
                data2[i, j] = data[i, j];
            }
        }
        watch.Stop();
        Console.WriteLine("Loop-copy to 2 dimensional array took {0} ms", watch.ElapsedMilliseconds);
    }
}

Output:

BlockCopy to flat array took 14 ms
BlockCopy to 2 dimensional array took 28 ms
Loop-copy to 2 dimensional array took 149 ms

Answer 3

Yes. However, it doesn't work the way you are thinking it works. Rather, it thinks of each mutlidimensional array as a single-dimensional array (which is actually what they are in memory, it's just a trick that lets us place some structure on top of them to think of them as multidimensional) and then copies the single-dimensional structures. So if you have

1 2 3
4 5 6

and want to copy it into

x x x x
x x x x

then it will think of the first array as

1 2 3 4 5 6

and the second as

x x x x x x x x

and the result will be

1 2 3 4 5 6 x x

which will appear to you as

1 2 3 4
5 6 x x

Got it?

Answer 4

Simple use the "Clone()" function like the following:

This is your array list

object newArray = new object [row, column];

When you are creating another Array just use this code:

object[,] clonedArray = (object[,]) newArray.Clone();

Simple! Have fun!