Comment by jstimpfle

What will you do on your 200th birthday?

In case you're more interested in theory than practice, I have a different answer: I use a different API.

However, I'm aware not even that could stop you, because you could still ask "what do you do when the strings might have more than SIZE_MAX characters?", which is entirely possible (as a combination of 2 or more strings).

And to answer that, we're coming back to my original answer: It doesn't happen. I'm not calling the API with such huge strings. (And no, I usually don't keep formal proofs that it couldn't happen -- there are also an infinite number of other properties that I don't verify).