quck question about typedef

This is a discussion on quck question about typedef within the C Programming forums, part of the General Programming Boards category; is this: Code: typedef struct node node_t; struct node { data_t data; node_t *next; }; the same as this: Code: ...

  1. #1
    Temporal Apparition qubit67's Avatar
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    quck question about typedef

    is this:
    Code:
    typedef struct node node_t;
    
    struct node {
    	data_t data;
    	node_t *next;
    };
    the same as this:
    Code:
    typedef struct node {
    	data_t value;
    	node_t *next;
    } node_t;
    ....?

  2. #2
    Deathray Engineer MacGyver's Avatar
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    More or less, yes.

    If you're defining a struct, I believe you have to refer to it by its formal name, however. Meaning that you can't write node_t *next, but would rather have to write it as struct node *next.

  3. #3
    Registered User divineleft's Avatar
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    Quote Originally Posted by MacGyver View Post
    More or less, yes.

    If you're defining a struct, I believe you have to refer to it by its formal name, however. Meaning that you can't write node_t *next, but would rather have to write it as struct node *next.
    are you sure?

    edit: oh, you meant inside the actual struct itself

  4. #4
    Deathray Engineer MacGyver's Avatar
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    Yes, sorry, I meant actually inside the struct itself when you define it. Outside of the actual struct definition, you can do whatever you want with typedefs.

  5. #5
    Just Lurking Dave_Sinkula's Avatar
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    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
    Temporal Apparition qubit67's Avatar
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    tnx pplz

  7. #7
    Registered Abuser
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    I've always been curious, is it possible for an anonymous structure to reference itself (i.e. while typedefing it)? I've always found it redundant to give a structure a name that I intend to typedef, and thus never use the structure name ever again. Something along the lines such as this:

    Code:
    typedef struct
    {
        (what to put here?) *ptrAnon;
    } anon;
    At first I thought to just redefine the anonymous struct again while specifying the type of its the pointer ptrAnon, i.e:
    Code:
    typedef struct
    {
        struct{...} *ptrAnon;
    } anon;
    but then that gets funny fast:
    Code:
    typedef struct
    {
        struct{struct{struct{... ad infinitum} *ptrAnon} *ptrAnon} *ptrAnon;
    } anon;
    Now this may very well be the most redundantly stupid question ever, but is it absolutely necessary to give a structure a name if you intend to reference it within itself, or in other words, can an anonymous structure contain a reference to itself?

  8. #8
    Woof, woof! zacs7's Avatar
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    Why wouldn't you name your structure though?

    Theres no harm from doing so...

  9. #9
    Deathray Engineer MacGyver's Avatar
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    Code:
    typedef struct
    {
    	struct node_t *next;
    } node_t;
    The above works with LCC.

  10. #10
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    Quote Originally Posted by zacs7 View Post
    Why wouldn't you name your structure though?
    Theres no harm from doing so...
    Its just all moot really, sort of like anonymous classes in java, you could name them.. but why bother coming up with a unique name if you never intend to use it again.

    Quote Originally Posted by MacGyver View Post
    Code:
    typedef struct
    {
    	struct node_t *next;
    } node_t;
    The above works with LCC.
    Cool, thanks, I'll have to try that out in gcc now.
    ..
    And it works! Awesome!
    Finally no more weird internal names for structures I want to typedef!
    Now I wonder how portable it is... though I'm guessing if its supported in GCC and LCC it's probably standard.

  11. #11
    Woof, woof! zacs7's Avatar
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    Depends what flags you used to compile it, why not read the C89 standard regarding structures?

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