warning: multi-character character constant...help me!

Discussion in 'C Programming' started by mimmo, Apr 10, 2004.

  1. mimmo

    mimmo Guest

    Hi! I should convert the accented letters of a string in the correspondent
    letters not accented. But when I compile with -Wall it give me:

    warning: multi-character character constant

    Do the problem is the charset? How I can avoid this warning? But the worst
    thing isn't the warning, but that the program doesn't work! The program
    execute all other operations well, but it don't print the converted
    letters: for example, in the string "licia colò" (with finally o accented),
    instead giving in stdout "licia colo" (without finally o accented), how
    should be, print "licia col ", with two spaces.
    The code is this:


    93 switch(s) {
    94 case 'à':
    95 t = 'a';
    96 break;
    97 case 'è': case 'é':
    98 t = 'e';
    99 break;
    100 case 'ì':
    101 t = 'i';
    102 break;
    103 case 'ò':
    104 t = 'o';
    105 break;
    106 case 'ù':
    107 t = 'u';
    108 break;
    109 default:
    110 break;
    111 }


    Between the apexes there are the accented letters. I try also with sprintf(t
    + i, "a") instead of t = 'a', but it's the same thing. If instead of
    accented letters I try to insert the unaccented letters, all works good.
    The output of the gcc is this:


    [mimmo@localhost mimmo]$ gcc -Wall p.c -o p
    p.c:94:38: warning: multi-character character constant
    p.c:97:38: warning: multi-character character constant
    p.c:97:49: warning: multi-character character constant
    p.c:100:38: warning: multi-character character constant
    p.c:103:38: warning: multi-character character constant
    p.c:106:38: warning: multi-character character constant
    [mimmo@localhost mimmo]$


    I hope anyone can give me an help, before than I drop the computer out
    mimmo, Apr 10, 2004
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  2. Your compiler apparently doesn't like the accented characters. If you are
    writing your translation for a specific codepage, you can use the relevant
    character codes (e.g. 0xa0 for a acute). You could also improve your code by
    using translation tables instead of a hardcoded switch, that way you have
    your way open for multiple codepages.

    Peter Pichler, Apr 10, 2004
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  3. mimmo

    mimmo Guest

    Your compiler apparently doesn't like the accented characters.

    My compiler is gcc 3.3.2, how is possible the problem is the compiler?
    Anyway I try to use the relevant character codes. Thank you!
    mimmo, Apr 10, 2004

  4. The fact that the message warns about a "multi-character character
    constant" (the kind of warning I'd expect for something like 'xy'), I
    don't think it's *just* a matter of not liking accented characters.
    My best guess is that you're using a UTF-8 encoding, which encodes
    Unicode characters in multiple bytes. Your text editor is correctly
    interpreting the UTF-8 sequences and displaying them for you as
    accented characters, but gcc apparently doesn't handle them.

    gcc may have an option to accept UTF-8 in source files; check the gcc
    documentation. Or you may be able to translate your UTF-8 source
    files to something like ISO-8859-1, which represents each character as
    a single byte (but doesn't handle the full range of Unicode).

    If you can't find the details in your documentation, try a newsgroup
    specific to your operating system.
    Keith Thompson, Apr 10, 2004
  5. mimmo

    josh Guest

    You're using a multi-byte character set, possibly UTF-8. The accented
    characters are occupying more than a single char each. See if you have
    library functions for dealing with UTF-8 characters and rethink your
    algorithm. (you can't scan one char at a time, you need to go by code

    The warning is because you are putting more than a single char between the
    ''s. The interpretation of this depends on endianness. Worse yet, since
    the resulting constant won't fit in a single char, you'll never properly
    match the input character.

    String processing is a real pain...

    josh, Apr 10, 2004
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