_JoyDef and _Control

Discussion in 'C Programming' started by Displacer, Oct 13, 2006.

  1. Displacer

    Richard Bos Guest

    Sure. As long as it's ISO C, and not a problem with, say, the POSIX
    libraries, comp.lang.c is the place for it. And if not, we'll usually
    know where the place is.

    Richard
     
    Richard Bos, Oct 16, 2006
    #21
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  2. Displacer said:

    Yes, that's fine. Obviously, it makes sense to try to work it out yourself
    first, using your C book as a guide (if it's a good book!), but to post
    questions about C syntax is very common and widely accepted here. Nobody -
    er, make that "almost nobody"! - will criticise you for asking C questions
    in a C newsgroup.
     
    Richard Heathfield, Oct 16, 2006
    #22
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  3. Displacer

    Richard Guest

    Except McCormack's reply, albeit tongue in cheek and inflammatory, was
    right about one thing. This was not a C question : it was about
    compiling a platform specific DOS game using a specific compiler and
    platform compiler specific subsystem specific libraries. Off Topic.
     
    Richard, Oct 16, 2006
    #23
  4. Displacer

    Displacer Guest

    Yes, thats what I'm doing, and by looking over someone elses source
    with a reference book at my side I'm learning quite a bit.

    With that said it appears this source is relying on the compiler to
    declare some of its code for it (guess this was common in the past)
    anyway heres what I have in the .h file:

    #define LEVELZONESIZE 250000

    And in the .c file:

    static levelzonesize=LEVELZONESIZE;

    which triggers a warning. Should I make this:

    static int levelzonesize=LEVELZONESIZE;
    or
    static long levelzonesize=LEVELZONESIZE;

    or does it matter which?
     
    Displacer, Oct 16, 2006
    #24
  5. Displacer

    Displacer Guest

    Yes I know now and have spanked myself accordingly ;)
     
    Displacer, Oct 16, 2006
    #25
  6. Displacer said:

    C guarantees that ints can represent values in the range -32767 to +32767 -
    you might get a wider range or you might not. But long ints are guaranteed
    to represent values in the range -2147483647 to +2147483647.

    So the answer is: the second one.
     
    Richard Heathfield, Oct 16, 2006
    #26
  7. Displacer

    Displacer Guest

    Thats what I thought as the define was for 250000
    Thanks!
     
    Displacer, Oct 16, 2006
    #27
  8. In C90 and earlier, a declaration with no type defaults to int
    ("implicit int"). C99 removed this feature, and it wasn't a very good
    idea even in C90.
    It matters which, but it's not clear which you should use. If you
    want to be sure levelzonesize can hold the value 250000 on all
    platforms, you need to declare it as long; int is only guaranteed to
    be able to hold values in the range -32767 .. +32767. But if other
    code in the program assumes levelzonesize is an int, for example:

    printf("levelzonesize = %d\n", levelzonesize);

    then changing levelzonesize to long could break such code.

    The safest approach is to make levelzonesize a long, then go through
    the entire program and check all references to it.
     
    Keith Thompson, Oct 16, 2006
    #28
  9. IMO, the problem wasn't "implicit int" but the LALR(1) conflict created when
    typedef's were added to C.


    Rod Pemberton
     
    Rod Pemberton, Oct 16, 2006
    #29
  10. Who says there can't be more than one problem?

    In my opinion, taking advantage of C90's permission to omit the
    keyword "int" in a declaration is a bad idea. It's always better to
    specify "int" explicitly. One reason is that using implicit int makes
    code incompatible with C99. Another is that avoiding implicit int
    makes the code clearer and more explicit.

    (I'm not saying that supporting implicit int in the C90 standard was a
    bad idea; it was necessary to support existing code.)

    The syntactical issues created by typedef (which was added long before
    C90) are another problem; I don't see how that's related to implicit
    int.
     
    Keith Thompson, Oct 16, 2006
    #30
  11. I agree.

    But, if it weren't for typedef's, we'd still have a default type of implicit
    ints, because they don't create any serious language issues without
    typedef's.

    Also, if we want to completely eliminate ambiguity in the grammar (true
    LALR(1)) we need two more tokens. One for an explicitly terminated if and
    another for the use of a typedef as a type qualifier since we can't use
    'typedef' itself (i.e., typedefname).

    As I said to Torek (using an example of his), it's very easy to fix the
    grammar:

    #define typedefname ut
    typedef int x;
    int *a;
    ut x *b; /* typedefname x *b */
    int **p = &b;

    void f(x); /* int x */
    void f(ut x); /* typedefname x */

    It's even portable:

    #define ut
    It was my understanding (?), that implicit int's were removed to help solve
    the ambiguities of a determining an implicit int versus a typedef.

    C++ "GETTING RID OF DEFAULT INT" 3)b) :
    http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1993/N0358.asc


    From what I'm able to locate, it appears that typedef's were added after
    implicit int's.

    C in 1977 or so, typedef's added:
    http://www.darwinsys.com/history/hist.html

    C in 1974-5 has implicit int's, but no typedef's ("13. Implicit
    declarations"):
    http://cm.bell-labs.com/cm/cs/who/dmr/cman.pdf
    http://cm.bell-labs.com/cm/cs/who/dmr/cman74.pdf


    Rod Pemberton
     
    Rod Pemberton, Oct 17, 2006
    #31
  12. (Why "ut"?)

    Yes, I suppose requiring "typedefname foo" rather than just "foo"
    would probably solve the syntax problem -- though it would largely
    defeat some of the purpose of having typedefs in the first place. At
    least nobody would bother with:

    typedef struct foo { ... } foo;

    if it only meant being to refer to the type as either "struct foo" or
    "typedefname foo".
    It's always been my assumption that implicit int was removed just
    because it's ugly (my word, not the committee's). The web page you
    cited (which, BTW, discusses C++ not C, but the issues are very
    similar) gives 4 major reasons for getting rid of implicit int. Two
    of them have nothing to do with parsing issues, and IMHO those are the
    strongest reasons.
    Right, so C has had implicit int since time immemorial, and typedef
    since 1977 or so. It survived from 1977 to 1999 with both typedef and
    implicit int. And removing implicit int has not, as far as I can
    tell, completely solved the typedef problem. For example,
    "sizeof(foo)" goes through a different grammatical production
    depending on whether "foo" is currently a typedef name or not. (I'm
    too lazy to come up with a better example right not.)
     
    Keith Thompson, Oct 17, 2006
    #32
  13. Grrrr. Somebody get up on the wrong side of the broom this morning?
     
    Kenny McCormack, Oct 24, 2006
    #33
  14. Displacer

    Jordan Abel Guest

    Yes, well... in his (rather dubious) defense, he wasn't saying _you_
    were in any way mentally ill, he was saying that the rest of us were for
    caring about on-topic-ness, and "trying" to be "helpful" by "explaining"
    our reaction.
    Yeah, well he is a bit of a...

    nevermind.
     
    Jordan Abel, Oct 24, 2006
    #34
  15. Plus the fact, and I've been meaning to point this out for a while now,
    I don't think most people think of wikipedia as a "site on mental
    illness". I know people around here (clc) don't much care for
    wikipedia, but I doubt many would go far as to say it is a site for
    crazy people.
     
    Kenny McCormack, Oct 24, 2006
    #35
  16. Displacer

    Displacer Guest

    On Tue, 24 Oct 2006 19:45:50 +0000 (UTC),
    I was refering to the link to aspergers
     
    Displacer, Oct 25, 2006
    #36
  17. I'm sure he knows perfectly well what you were referring to.

    Kenny McCormack is a self-proclaimed troll. *Please* ignore him.
     
    Keith Thompson, Oct 25, 2006
    #37
  18. Keith Thompson is a self-proclaimed netcop. *Please* ignore him.
     
    Kenny McCormack, Oct 25, 2006
    #38
  19. I'd rather read anything Keith Thompson writes than anything Kenney McComack
    writes - rationality takes precedence over the Celtic soul botherhood.
     
    Paul Connolly, Oct 27, 2006
    #39
  20. As you wish. But I haven't seen KT post anything other than "Off topic,
    can't discuss it here, blah, blah, blah" (of course not in those
    specific words) in, literally, years.
     
    Kenny McCormack, Oct 27, 2006
    #40
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