How to initialize a multidimensional array

int[][] is a jaggad array, which means that every array can be in a different size. This is why you can initialize it that way:

    int[][] arr2D= new int[3][];
    arr2D[0] = new int[0];
    arr2D[1] = new int[1];
    arr2D[2] = new int[2];

which will create a 2d array that looks like this:

_
_ _
_ _ _

The following is an example to create 3d jaggad array (with different sizes for each dimension- 5 rows, 3 columns and 6 depth):

    int[][][] arr3D = new int[5][][];
    for (int col = 0; col < arr3D.Length; col++)
    {
        arr3D[col] = new int[3][];
        for (int depth = 0; depth < arr3D[col].Length; depth++)
        {
            arr3D[col][depth] = new int[6];
        }
    }

In order to get the dimension size in jaggad array, you can simply get the lenth of the array, but keep in mind that if the array is actually jagged, you will have different sizes for different arrays. if you initialize all of the arrays in a specific dimension with the same value, than you can check either of them, it will be the same.

int[,] is a multi dimensional array that every dimension have a fixed size. To create a multi dimensional: int[,] arr2D = new int[3,4];

which will create a 2d array looking like this:

_ _ _ _
_ _ _ _
_ _ _ _

In multi dimensional array you can't change the length of a specific row or column.

In most cases you will probably prefer a multi dimensional array.

In order to get the size of a specific dimension in a multi dimensional array, you can use the following method: int rows = arr22.GetLength(0); int cols = arr22.GetLength(1); int depth = arr22.GetLength(2);

The input is the dimension you want the size of.

You can do:

new int[][][] myArray = new int[][][] 
{
    new int[][] 
    {
        new int[] 
        {
            // Your numbers
        }
    }
}

myArray[0].Length
myArray[0][0].Length
myArray[0][0][0].Length

Works fine

You can't declare a jagged array in one line like this: new int[sizeX][sizeY][sizeZ]; as you really have three levels of nested arrays. You need to initialize them at each level.

This is what that would look like:

void Set3DArraySize(int sizeX, int sizeY, int sizeZ)
{
    my3DArray = new int[sizeX][][];
    for (var x = 0; x < sizeX; x++)
    {
        my3DArray[x] = new int[sizeY][];
        for (var y = 0; y < sizeY; y++)
        {
            my3DArray[x][y] = new int[sizeZ];
        }
    }
}

Now, if you do want to initialize a multidimensional array, you can do this:

int[,,] z =
{
    { { 1, 2, }, { 1, 2, }, { 1, 2, }, },
    { { 1, 5, }, { 1, 5, }, { 2, 8, }, },
    { { 1, 5, }, { 1, 5, }, { 2, 8, }, },
    { { 1, 5, }, { 1, 5, }, { 2, 8, }, },
};

And then, to get the dimensions, you can do this:

Console.WriteLine(z.GetLength(0));
Console.WriteLine(z.GetLength(1));
Console.WriteLine(z.GetLength(2));

That gives me:

4
3
2

It's important to note that with a jagged array each nested array can be of different length, but with a multidimensional array then each dimension must be uniform.

For example, a jagged array could look like this:

int[][] y = new int[][]
{
    new [] { 1, 2, },
    new [] { 1, 2, 3, },
    new [] { 1, },
};

And a multidimensional array like this:

int[,] y =
{
    { 1, 2, 3, },
    { 4, 5, 3, },
    { 1, 6, 3, },
    { 1, 7, 8, },
};

I could not do this:

//illegal!!!
int[,] y = 
{
    { 1, 2, 3, },
    { 4, 5, 3, 7, },
    { 1, 6, },
    { 1, 7, 8, },
};

void Set3DArraySize(int sizeX, int sizeY, int sizeZ)
{
   my3DArray = Enumerable.Repeat(Enumerable.Repeat(new int[sizeZ], sizeY).ToArray(),sizeX).ToArray();
}