Array of what? You need a
type for your array elements.
int arr[10][10][10];
In practice this may not to be a good idea as it can complicate the array access code somewhat and it has very little advantage if any over
int arr[1000];
There's nothing to stop you treating this as a multidimensional array any you may find the code actually turns out to be easier to write.
Up to you really which you prefer.