Multi-Dimensional Array - Array of arrays?

Question

I have a string containing numbers as a 2D matrix. I'm trying to use Split function to split the contents of a string into an array. So, when I do:

String[] subStrs = new String[20];
subStrs = str.Split('\n'); 

The code above works fine. However, when I try to create a 2D array and try to populate sub-arrays using the same way:

String[,] numbers = new String[20,20];
for (int i = 0; i < subStrs.Length; i++ )
{
    numbers[i] = subStrs[i].Split(' '); //Error
}

I get the following compiler error:

Wrong number of indices inside []; expected 2.

If 2D array is really an array of arrays, then why is the statement numbers[i] = subStrs[i].Split(' '); illegal?

PS : I do know that I can use a nested loop instead to populate numbers . I'm just curious why can't I use the above method?

Answer 1

If 2D array is really an array of arrays

It's not. A 2D array is just that, a 2D array.

An array of arrays is an array of arrays:

string[][]

If you have an array of arrays, then the item at each index of the outer array is another array. If you have a 2D array then both dimensions are needed to get at a value, which is itself the value of the array, not another dimension.