Array question about [,] vs [][]

Here is an example of each type of array. In the first example we have a Matrix [x,y] type array. these arrays are like excel spreadsheets or a piece of graphpaper. these cannot be sliced. they have an advantage in that they are easier to set up and more intuitive (for me at least) to use:

[X,Y]

0,1,2,3,4
0,1,2,3,4
0,1,2,3,4
0,1,2,3,4

SuperStrict
Local xcells:Int = 10
Local ycells:Int = 10
		
Local map:Int[xcells,ycells]

	Print Len(map)
	For Local CX:Int = 0 To xcells-1
		For Local CY:Int = 0 To ycells-1 
			map[CX,CY] = CY
			
		Next
		
	Next
	Print "created" +xcells*ycells

For Local CX:Int = 0 To xcells-1
		Print "Map["+CX+"]"
		For Local CY:Int = 0 To ycells-1 
			Print "    Map["+CX+","+CY+"]="+map[CX,CY] ' "CX:"+CX+" CY:"+CY
			

		Next
		
	Next
	

This is an Array of Arrays [X][Y]. these offer much more flexibility. (can be sliced, can be resized) but require more setup and are less intuitive. Check out the output for Element Map[3] after the resize:

[X] [....Y.....]
[0] [0,1,2,3,4]
[1] [0,1,2,3,4]
[2] [0,1,2,3,4]
[3] [0,1,2,3,4,5,6,7,8,9...]
[4] [0,1,2,3,4]

SuperStrict
Local xcells:Int = 5
Local ycells:Int = 5
		
Local map:Int[][]

map = map[..xcells]
		
	For Local this_cell:Int = 0 To xcells - 1
			map[this_cell] = map[this_cell][..ycells]
	Next
		
	map = map[..xcells][..ycells]
	Print Len(map)
	For Local CX:Int = 0 To xcells-1
		For Local CY:Int = 0 To ycells-1 
			map[CX][CY] = CY
			
		Next
		
	Next
	Print "created" +xcells*ycells

For Local CX:Int = 0 To xcells-1
		Print "Map["+CX+"]"
		
		For Local CY:Int = 0 To Len(map[CX])-1 
			Print "    Map["+CX+"]["+CY+"]="+map[CX][CY] ' "CX:"+CX+" CY:"+CY
			

		Next
		
	Next
Print "*************** Resize of Map[3] to 25 elements ( Map[3][..25] ) **************"
' you can resize at any time.
map[3] = map[3][..25]
	
For Local CX:Int = 0 To xcells-1
		Print "Map["+CX+"]"
		
		For Local CY:Int = 0 To Len(map[CX])-1 
			Print "    Map["+CX+"]["+CY+"]="+map[CX][CY] ' "CX:"+CX+" CY:"+CY
			

		Next
		
	Next

So the Biggest advantage of 'Array of Arrays' is that they can be resized, sliced, diced etc. you can start off with an emty array[][] and resize it from within your program.