In the documentation one can learn how to do array operations with 1D arrays. However, this does not scale up for 2D arrays. For example, the following does not work:

int[2][2] a,b;
a = [[1,1],[1,1]];
b[][] = a[][]*2;


Additionally, I would like to assign 2D sub-arrays of a 3D array, i.e. something like the following:

int[3][2][2] a;

a[0] = [[2,2], [2,2]];


I did not understand how to use std.experimental.ndslice to do this. An example would be greatly appreciated.

On Saturday, 19 November 2016 at 10:20:16 UTC, Marduk wrote:
> Additionally, I would like to assign 2D sub-arrays of a 3D array, i.e. something like the following:
>
> int[3][2][2] a;
>
> a[0] = [[2,2], [2,2]];

You have the dimensions the wrong way around. a is a 2 element array of 2 element arrays of 3 element arrays.

int[3][2][2] a;
a[0] = [[2,2,2], [2,2,2]];

works fine.

On Saturday, 19 November 2016 at 17:37:58 UTC, John Colvin wrote:
> On Saturday, 19 November 2016 at 10:20:16 UTC, Marduk wrote:
>> Additionally, I would like to assign 2D sub-arrays of a 3D array, i.e. something like the following:
>>
>> int[3][2][2] a;
>>
>> a[0] = [[2,2], [2,2]];
>
> You have the dimensions the wrong way around. a is a 2 element array of 2 element arrays of 3 element arrays.
>
> int[3][2][2] a;
> a[0] = [[2,2,2], [2,2,2]];
>
> works fine.

Thanks a lot! Now I get what it means that array declarations are read from right to left.

On Saturday, 19 November 2016 at 19:36:50 UTC, Marduk wrote:
> On Saturday, 19 November 2016 at 17:37:58 UTC, John Colvin wrote:
>> On Saturday, 19 November 2016 at 10:20:16 UTC, Marduk wrote:
>>> Additionally, I would like to assign 2D sub-arrays of a 3D array, i.e. something like the following:
>>>
>>> int[3][2][2] a;
>>>
>>> a[0] = [[2,2], [2,2]];
>>
>> You have the dimensions the wrong way around. a is a 2 element array of 2 element arrays of 3 element arrays.
>>
>> int[3][2][2] a;
>> a[0] = [[2,2,2], [2,2,2]];
>>
>> works fine.
>
> Thanks a lot! Now I get what it means that array declarations are read from right to left.

The way I think about it is this:

int is a type. int[3] is an array of 3 ints. Similarly, int[3] is a type, so an array of 2 int[3]s is int[3][2] and so on...

On Saturday, 19 November 2016 at 21:05:49 UTC, John Colvin wrote:
> On Saturday, 19 November 2016 at 19:36:50 UTC, Marduk wrote:
>> Thanks a lot! Now I get what it means that array declarations are read from right to left.
>
> The way I think about it is this:
>
> int is a type. int[3] is an array of 3 ints. Similarly, int[3] is a type, so an array of 2 int[3]s is int[3][2] and so on...


 A while back I was writing a Sudoku solver which used static array types. It went something like this:

 alias Possible = byte[10]; //1-9 possible, plus final known value
 alias Block = Possible[9];
 alias Sudoku = Block[9];

 Actual Sudoku: byte[10][9][9]

 While this breaks down easily enough, if the order had been the other way around it wouldn't have been extensible this way to making larger structures from basic types/arrays.