Yeah, that's a really bad example... many environments now don't have a "string reversal" anymore, and many of the ones that do are the old & busted "string reverse" that doesn't work with Unicode, so they aren't really "string reverse" but just a legacy function that can't be removed anymore that is now technically grotesquely mislabeled. A modern-day string reverse is barely even defineable; technically, you have to pin it to a specific version of the Unicode standard to be well-defined because the next standard is likely to add characters that your string reverse would need to know about to work properly, but can't since they don't exist yet.
In some sense the best answer to "write me a string reversal function" in an interview is to say that no such function even exists anymore; I can write you a byte reversal function if you like, or we can sit down and hammer out a definition of some function I can write for you but it won't necessarily be a "string reverse". Best you can do nowadays is iterate on "graphemes as defined in this specific Unicode standard" and reverse those, but IIRC even that has some pathological edge cases, some of which are not really resolvable. Human languages as a whole are quite quirky.
In some sense the best answer to "write me a string reversal function" in an interview is to say that no such function even exists anymore; I can write you a byte reversal function if you like, or we can sit down and hammer out a definition of some function I can write for you but it won't necessarily be a "string reverse". Best you can do nowadays is iterate on "graphemes as defined in this specific Unicode standard" and reverse those, but IIRC even that has some pathological edge cases, some of which are not really resolvable. Human languages as a whole are quite quirky.