concepts on 3d array

[AngKar]

Could anyone please clear the following ideas regarding a 3d array to me?

1. for an array, int arr[i][j][k], does arr++ mean anything?
2. is cube (or a rectangular parallelepiped to be precise) a correct reperesentation of a 3d array? if so, how can i increment/decrement a particular cell data, say data at 1,2,2?

Thanks,
Angshu

[Slacker]

>1. for an array, int arr[i][j][k], does arr++ mean anything?
Nope, it's an error.

>2. is cube (or a rectangular parallelepiped to be precise) a correct reperesentation of a 3d array?
You can think of it that way if you want, but in memory a 3 dimensional array is just a one dimensional array with a little extra stuff to make indexing work like the cube representation.

>how can i increment/decrement a particular cell data, say data at 1,2,2?

++arr[1][2][2];

[dwks]

>1. for an array, int arr[i][j][k], does arr++ mean anything?
Nope, it's an error.

However, it does mean something on a pointer, such as int ***p. Just like with 1D and 2D arrays.

[Slacker]

>However, it does mean something on a pointer, such as int ***p.
However, the question wasn't about a pointer, it was about an array.

[quzah]

However, it does mean something on a pointer, such as int ***p. Just like with 1D and 2D arrays.

Also, since we're at it, you're a bit misleading here. This statement implies that incrementing a pointer has the same, or similar, effect as incrementing 1D and 2D arrays. Which of course is false, because you can't do: arrayname++, no matter how many dimensions it has.


Quzah.

[cwr]

Another way it's misleading is dwks' statement implies that if you have an array:

int a[50][50][50];
int b[50];

And then you have:

int ***p = a;
int *q = b;

Then p++ will be useful in traversing the array, and it isn't. Though q++ is.