How do I determine the character set of a string?
I have several files that are in several different languages. I thought they were all encoded UTF-8, but now I'm not so sure. Some characters look fine, some do not. Is there a way that I can break out the strings and try to identify the character sets? Perhaps split on white space then identify each word? Finally, is there an easy way to translate characters from one set to UTF-8?
If you don't know the character set for sure You can only guess, basically. utf8::valid might help you with that, but you can't really know for sure. If you know that if it isn't unicode it must be a specific character set (Like Latin-1), you lucky. If you have no idea, you're screwed. In any case, you should always assume the whole file is in the same character set, unless otherwise specified. You will lose your sanity if you don't.
As for your question how to convert between character sets: Encode is there to do that for you
Determining whether a file is probably UTF-8 or not should be pretty easy. Determining the encoding if it is not UTF-8 would be very difficult in general.
If the file is encoded with UTF-8, the high bits of each byte should follow a pattern. If a character is one byte, its high bit will be cleared (zero). Otherwise, an n byte character (where n is 2–4) will have the high n bits of the first byte set to one, followed by a single zero bit. The following n - 1 bytes should all have the highest bit set and the second-highest bit cleared.
If all the bytes in your file follow these rules, it's probably encoded with UTF-8. I say probably, because anyone can invent a new encoding that happens to follow the same rules, deliberately or by chance, but interprets the codes differently.
Note that a file encoded with US-ASCII will follow these rules, but the high bit of every byte is zero. It's okay to treat such a file as UTF-8, since they are compatible in this range. Otherwise, it's some other encoding, and there's not an inherent test to distinguish the encoding. You'll have to use some contextual knowledge to guess.