Comment by sigsev_251
3 months ago
Yes, but is one allowed to move a pointer inside it as they see fit? On a one-dimensional array, one can iterate through it starting with a pointer pointing to the first element and ending with a pointer pointing one position past the last element (which the user is not allowed to dereference). For multidimensional arrays, the element type is an array too (with a smaller rank than the original one), so one could perform that type of iteration with a pointer to an array. My question is whether a pointer to the underlying scalar type can freely move inside the multidimensional array without UB, since it may have to actually leave the array it was originally part of. If that's not allowed, how could one build slices and other view types?
Yes, you can do that, it's fine as long as you stay within the bounds of the indexes. Under the hood, it's a single contiguous block of memory.
Although at least with 2d arrays I prefer to just use a 1d array and index it with [x * width + y], because one problem with multidimensional arrays in C is they need multiple allocations/frees.
Why would you need multiple allocations?
edit: Isn't it just:
You have to allocate the size for m and n, because C arrays decay bare pointers.
But it seems to work, which I didn't expect[0]. It also seems like you have to de-reference it to use it which is weird.
[0]https://onlinegdb.com/HwX-WTL5t
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