4 ms·

> The C way I know focuses mainly on character at a time iteration Ah, yes, the good 'ole C way that only works reliably in English.

• dbaupp 10y ago
  It's a little naïve to think it works on English without the coöperation of the users. (Also, less glibly, things like emoji seem to be becoming more and more popular.)
  • imron 10y ago
    Indeed. In fact as we speak I am fixing a bug related to string handling with emojis.
• asveikau 10y ago
  Funny. You can parse utf-8 character at a time. Some characters advance the pointer by 4 at an iteration and some less.
  • dbaupp 10y ago
    What do you mean by "character"? If you mean code point or "unicode scalar value", sure, but if you mean user-visible character (grapheme), it's much more complicated: even something "simple" like ö could be one or two code points.
    • asveikau 10y ago
      I mean your iterator is char* and you advance it by adding. That's it. I do NOT mean that char itself corresponds to a glyph or codepoint, you are seriously preaching to the choir making that lecture to me.
      • fauigerzigerk 10y ago
        >you advance it by adding And when do you stop? UTF-8 strings can have zero bytes in them so treating them as C strings is potentially error prone depending on the context.
        • asveikau 10y ago
          Unless you have U+0000 there isn't any other sequence of code points that has an 0x00 byte in UTF-8. I don't see this as a huge problem. If you really do need it there are some C language libraries that use "pascal-ish" structs to do strings. UNICODE_STRING in Windows comes to mind. Doing strings in C doesn't force you to use C strings, it's just the most common thing to do.
          • fauigerzigerk 10y ago
            No it's not a huge problem, but if you're not aware of it, it could easily lead to a security breach: https://news.ycombinator.com/item?id=13974919 https://news.ycombinator.com/item?id=13974919
        • MichaelGG 10y ago
          It's the same for ASCII - UTF-8 zero byte is NUL.
        • imron 10y ago
          > UTF-8 strings can have zero bytes in them This is not true. A zero-byte in a utf-8 string is the null-terminator and utf-8 strings can be treated exactly like C strings in terms of where the string ends. What you do need to look out for is malformed utf-8, for example, 1 byte before the null terminator you get a lead byte saying the next character is 4-bytes long. If you're not checking each byte for null and just skipping based on the length indicated by the lead byte then you're in for a crash. Where utf-8 strings differ from C strings is slicing. You can't just slice the string at some random point without doing extra validation to make sure you only slice on codepoint boundaries.
          • dbaupp 10y ago
  • imron 10y ago
    You can, and then you get a 4-byte long character 1-byte before the end of your data, you skip over the null-terminator and into the stack, and bang. Yes, you can avoid this if you're careful and you understand the intricacies of utf-8 (or some other multi-byte encoding), but it very quickly stops being elegant.
  • pikzen 10y ago
    What are combinators? Go parse some zalgo with your 4 per iteration algorithm. I'll be there, waiting and laughing. C string handling is not elegant, nor does it fit the realities of the world.
• cat199 10y ago
  So it's somehow C's fault that Unicode uses variable-length encoding, which is automatically going to be harder to process correctly at a byte-by-byte level than a fixed-length method, and also included known-C-incompatible null bytes?
  • imron 10y ago
    > So it's somehow C's fault that Unicode uses variable-length encoding Parent said string handling in C was elegant. My point is that it becomes fraught with (even more) issues once you throw non-English language at it. It is C's decision to handle strings in this way, and the decision of many C programmers to treat all strings as if they are just iterable character pointers. It's a recipe for bugs.
    • asveikau 10y ago
      I am the parent you are talking about. I've made this argument many times with people: Unicode is crazy complicated in any programming language. People think that widening the char width will help - well you seem to be somebody who knows Unicode so you probably know the horrors of surrogates, combining characters vs. pre-composed diacritics, zero-width joiners, Han unification, variation selectors, BiDi... This is in no way just a C thing to deal with all that nonsense. I've not seen any language or library that I'd say does it "well" and saves individual programmers from considering the above. They all punt the issue to the programmer. I've heard (mostly here) that Swift does something different and treats glyphs as the basic unit. I haven't had a chance to look at precisely what that does. Given all the issues I've seen elsewhere I'm skeptical that someone, anyone can pull that off correctly. UTF-8 at least has one elegance (there's that word again) in the design in that you can do some "dumb" ASCII things and if your code does not know what to do with fancy unicode, you can check the high bit of any given octet and "safely" skip over it and any adjacent nonascii sequence if you don't know what it means. This may or may not be applicable to a task at hand.
      • imron 10y ago
        > This is in no way just a C thing to deal with all that nonsense. I've not seen any language or library that I'd say does it "well" and saves individual programmers from considering the above. This is true, however even something as simple as storing the (byte) length as part of the string reduces the complexity and the likelihood for bugs. Other languages also prevent accidental buffer overruns so while they still need to deal with all the same Unicode problems you mentioned, the program likely won't crash if the programmer gets things wrong. The same is not necessarily true of C.