Structs in C

This is a discussion on Structs in C within the C Programming forums, part of the General Programming Boards category; Hi, I am trying to do the following: Code: typedef struct _STRUCT1 { integer var1[SIZE]; } STRUCT1 typedef struct _STRUCT2 ...

  1. #1
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    Structs in C

    Hi,
    I am trying to do the following:
    Code:
    typedef struct _STRUCT1
    {
            integer var1[SIZE];
    
    } STRUCT1
    
    typedef struct _STRUCT2
    {
           STRUCT1 var2(100);
           STRUCT1 var3(200);
    } STRUCT2
    I want that var2.var1 will have the array size=100
    and var3.var1 will have the array size=200;
    is it posible, or must i do this:

    Code:
    typedef struct _STRUCT1
    {
            integer var1[100];
    
    } STRUCT1
    
    typedef struct _STRUCT3
    {
            integer var1[200];
    
    } STRUCT3
    
    typedef struct _STRUCT2
    {
           STRUCT1 var2;
           STRUCT3 var3;
    } STRUCT2

  2. #2
    The C eater *munch*
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    have you compiled and see it yourself? tho i saw some problems with your struct definition

  3. #3
    Registered User SKeane's Avatar
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    Code:
    typedef int hun1[100];
    typedef int hun2[200];
    
    typedef struct _MYSTRUCT
    {
        hun1 var1;
        hun2 var2;
    } MYSTRUCT;

  4. #4
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    obvious that It's not working..
    it was just an hypothetical example.

    I am trying to do this now:

    Code:
    #define MACRO1(_SIZE,_NAME)    struct _NAME        \
                                                         {                                        \
                                                               INT32   var1[_SIZE];    \
                                                          }; 
    
    
    typedef struct _STRUCT2
    {
           MACRO1(100,var2)
           MACRO1(200,var3)
    } STRUCT2

  5. #5
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    maybe struct templates?
    any ideas?

  6. #6
    Registered User SKeane's Avatar
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    Code:
    #define MACRO1(_SIZE,_NAME) int _NAME[_SIZE];
    
    typedef struct _STRUCT2
    {
        MACRO1(100,var2)
        MACRO1(200,var3)
    } STRUCT2;

  7. #7
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    its just not possible to have 1 type representing 2 different sizes. other means are needed here.
    What would sizeof(struct _NAME) be?

  8. #8
    ATH0 quzah's Avatar
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    Look at the macro again. "_NAME" isn't a struct. It's the name of the variable you want your array to be called. Were I to use this, I'd probably reverse the arguments, but that's just me.


    Quzah.
    Hope is the first step on the road to disappointment.

  9. #9
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    Quote Originally Posted by quzah
    Look at the macro again. "_NAME" isn't a struct. It's the name of the variable you want your array to be called. Were I to use this, I'd probably reverse the arguments, but that's just me.


    Quzah.
    ah, I was responding to amitbern's post where _NAME is a struct. Theres many options to do this, but having 1 struct with 2 different sizes is just not one of them.

  10. #10
    Reverse Engineer maxorator's Avatar
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    When you define a structure, you need to define all the variables in it with all data sizes.
    So if you have already defined a structure, you can't just cast it with different sizes. It's already defined.

    If you're are going to have only one variable in the struct, think again. Why do you need struct then?
    "The Internet treats censorship as damage and routes around it." - John Gilmore

  11. #11
    ATH0 quzah's Avatar
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    Quote Originally Posted by maxorator
    When you define a structure, you need to define all the variables in it with all data sizes.
    No you don't. The last object in a structure is allowed to be an array of undefined size. The size field of the array is left blank. This is known as a flexible array member. It is allowed as of C99. However, it has its own rules, such as, said structure can not be part of an array.


    Quzah.
    Hope is the first step on the road to disappointment.

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