4 ms·

I don't know if the author is looking at this comment section but small issue: > Array: Implements a dynamic array similar to std::array in C++. should read "

by mauvia 3y ago

I don't know if the author is looking at this comment section but small issue: > Array: Implements a dynamic array similar to std::array in C++. should read "static array". std::array requires you to state the size. C++ std::arrays are pretty much just uniformly typed tuple structures, not dynamic arrays. In fact you can use them directly on the stack with no memory allocations whatsoever.

Arech 3y ago
Erm, actually, all STL implementations I've seen use a simple C-style array under the hood to store `std::array` data, not a much more complex tuple. But it doesn't matter much in the context of the question: the whole point of `std::array` is to provide fixed inplace storage for the data, basically just a safe version of a C-array. Implementing it on top of dynamically sized vector, like the author did, is... just missing the whole idea. This thing was the first I noticed while looking at the sources... And I don't want to look any more further now.
- quietbritishjim 3y ago
  I think that's what parent comment meant by "tuple": a list-like structure that can't be resized.
- mauvia 3y ago
  Dynamically allocated static array might be closer to truth for what they implemented, I think.
phire 3y ago
The real std::array is static. But c doesn't really have any way to do static arrays, so c_std has decided to implement a dynamic array with an api similar to the std::array. The documentation is correct regarding what c_std has actually implemented. And it's still useful, unlike vector the size is (dynamically) set once at construction and then enforced.
- jenadine 3y ago
  Of course C can do static array: int array[N]; is one.
  - quietbritishjim 3y ago
    But not an abstract data structure that can be allocated on the stack. (Your example can go on the stack. A struct with a final array member of unspecified size can work as an abstract data structure. But you can't have both at once.)
- mauvia 3y ago
  Well, std::array is meant to be a direct replacement for what jenadine mentioned, the C style of doing static arrays. I think under the hood it takes over the array initialization syntax as well (or array initialization of objects got added to the standard to support std::array?) and IIRC there are some functions that are simply unavailable to std::array because of its array based construction. I don't remember exactly what but I have run into it before, I think the iterator implementation is a raw pointer and that breaks the interface expectations a bit?

by mauvia 3y ago

Arech 3y ago

Erm, actually, all STL implementations I've seen use a simple C-style array under the hood to store `std::array` data, not a much more complex tuple. But it doesn't matter much in the context of the question: the whole point of `std::array` is to provide fixed inplace storage for the data, basically just a safe version of a C-array. Implementing it on top of dynamically sized vector, like the author did, is... just missing the whole idea. This thing was the first I noticed while looking at the sources... And I don't want to look any more further now.

quietbritishjim 3y ago
I think that's what parent comment meant by "tuple": a list-like structure that can't be resized.
mauvia 3y ago
Dynamically allocated static array might be closer to truth for what they implemented, I think.

phire 3y ago

The real std::array is static. But c doesn't really have any way to do static arrays, so c_std has decided to implement a dynamic array with an api similar to the std::array. The documentation is correct regarding what c_std has actually implemented. And it's still useful, unlike vector the size is (dynamically) set once at construction and then enforced.

jenadine 3y ago
Of course C can do static array: int array[N]; is one.
- quietbritishjim 3y ago
  But not an abstract data structure that can be allocated on the stack. (Your example can go on the stack. A struct with a final array member of unspecified size can work as an abstract data structure. But you can't have both at once.)
mauvia 3y ago
Well, std::array is meant to be a direct replacement for what jenadine mentioned, the C style of doing static arrays. I think under the hood it takes over the array initialization syntax as well (or array initialization of objects got added to the standard to support std::array?) and IIRC there are some functions that are simply unavailable to std::array because of its array based construction. I don't remember exactly what but I have run into it before, I think the iterator implementation is a raw pointer and that breaks the interface expectations a bit?