UTF-8 string literals

This is a discussion on UTF-8 string literals within the C Programming forums, part of the General Programming Boards category; What's the best way of embedding UTF-8 (specifically UTF-8, not Unicode) literals in strings in C? You can, of course, ...

  1. #1
    pdc
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    UTF-8 string literals

    What's the best way of embedding UTF-8 (specifically UTF-8, not Unicode) literals in strings in C? You can, of course, do them as byte (char) sequences, but that makes it impossible to write
    Code:
    char * str = "The first letter of the Greek alphabet is " ALPHA ".";
    Basically, I want to be able to write
    Code:
    #define ALPHA "<something>"

  2. #2
    pdc
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    I should probably add, since this is platform-dependent, that I'm using GCC on OS X and FreeBSD.

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    I can see two ways:
    1. declare utf-8 string as a byte array:
    Code:
     unsigned char utf8[] = { 'a', 'b', 0 };
    2. declare string as wide char string, then convert to multibyte.

  4. #4
    pdc
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    That doesn't work. As I said, representing them isn't the problem. Reresenting them as a string literal is. Can they be written as "<something>"?

  5. #5
    Just Lurking Dave_Sinkula's Avatar
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    Venturing into new territory myself, but isn't it something like "\u0139"?
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  6. #6
    Registered User Codeplug's Avatar
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    Using '\U' or '\u' is C99's support for Universal Character Names (UCN).

    The character set used is the Universal Character Set (UCS), as described by ISO/IEC 10646.

    You can also use 'u' or 'U' to begin a string literal (much like 'L').
    When you use 'u', you get a UTF-16 encoded character or string literal.
    When you use 'U', you get a UTF-32 encoded character or string literal.
    When you use 'L', you get a "wide" character or string. The character set used in implementation defined.

    You use wchar_t for all of those.

    If you want portable, UTF-8 encoding in a string literal, you'll have to encode it yourself with escape sequences "\xhhh".

    http://www.cl.cam.ac.uk/~mgk25/unicode.html

    Having said all that, here's gcc's "defined implementation"
    http://gcc.gnu.org/onlinedocs/gcc-4....fined-behavior

    If you lookup the "-fexec-charset", you'll find that UTF-8 is already the default. So if you have a Greek "Alpha" on your keyboard, make your source files UTF-8 and put the real character in there (gcc supports UTF-8 source files). If you're source files are in ASCII, you'll have to use escape sequences or load your strings from an external source.

    gg

  7. #7
    pdc
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    That's great, exactly what I was looking for, thanks!

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