array of structs

This is a discussion on array of structs within the C Programming forums, part of the General Programming Boards category; Hi All I tried to construct an array of structs, but it doesn't compile Code: #include <stddef.h> #include <stdlib.h> #include ...

  1. #1
    Registered User
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    May 2009
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    72

    array of structs

    Hi All

    I tried to construct an array of structs, but it doesn't compile

    Code:
    #include <stddef.h>
    #include <stdlib.h>
    #include <regex.h>
    #include <stdio.h>
    #include <string.h>
    
    struct Abc {
      int *x ;
    } *st ;
    
    int main(void) {
      st = malloc( 2 * sizeof(*st) ) ;
      st[0] = (struct Abc*)malloc(sizeof(struct Abc) ) ;
      st[1] = (struct Abc*)malloc(sizeof(struct Abc) ) ;
    }
    I guess I do something fundamentally wrong here! Any suggestions ?

    thnx
    LuCa

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    Canada
    Posts
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    Try this.
    Code:
    #include <stddef.h>
    #include <stdlib.h>
    
    struct Abc {
      int *x ;
    } ;
    
    int main(void) {
      struct Abc **st = malloc( 2 * sizeof(*st) ) ;
      st[0] = (struct Abc*)malloc(sizeof(**st) ) ;
      st[1] = (struct Abc*)malloc(sizeof(**st) ) ;
      return 0;
    }
    That creates an array of arrays with an Abc**.

    You can also do this.
    Code:
    #include <stddef.h>
    #include <stdlib.h>
    
    struct Abc {
      int *x ;
    } ;
    
    int main(void) {
      struct Abc *st = malloc( 2 * sizeof(*st) ) ;
      return 0;
    }
    Then st[0] is one element, and st[1] is another element. It's just that I've created an array of structures, not an array of pointers to dynamically allocated structures.
    dwk

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  3. #3
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    wow, thats fast, thanks a lot! I guess I still have to get used to pointers to pointers!

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