In the standard there's things like "exactly N operations", but not seeing stuff for `istream`. There's like... an explanation of how things should work and I imagine you can derive complexity from it, but I think `istream` is a bit special since you're talking about this wrapper for (potentially) an arbitrary input source.

[0]: https://eel.is/c++draft/alg.move#15

[1]: https://eel.is/c++draft/input.streams#istream.extractors-7

No, or at least not in general, because you can overload it for your custom types with whatever terrible implementation you like.

This is true in essentially the same way for C's FILE, which is the point I think Ted is insinuating.