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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3.  
  4. typedef struct _Foo_
  5. {
  6.     // variables
  7.     int number;
  8.     char character;
  9.  
  10.     // array of float
  11.     int arrSize;
  12.     float* arr;
  13.  
  14.     // pointer to another instance
  15.     void* myTwin;
  16. } Foo;
  17.  
  18. Foo* createFoo (int arrSize, Foo* twin);
  19. Foo* destroyFoo (Foo* foo);
  20.  
  21. int main ()
  22. {
  23.     Foo* a = createFoo (2, NULL);
  24.     Foo* b = createFoo (4, a);
  25.  
  26.     destroyFoo(a);
  27.     destroyFoo(b);
  28.  
  29. 	printf("success");
  30.     return 0;
  31. }
  32.  
  33. Foo* createFoo (int arrSize, Foo* twin)
  34. {
  35.     Foo* t = (Foo*) malloc(sizeof(Foo));
  36.  
  37.     // initialize with default values
  38.     t->number = 1;
  39.     t->character = '1';
  40.  
  41.     // initialize the array
  42.     t->arrSize = (arrSize>0?arrSize:10);
  43.     t->arr = (float*) malloc(sizeof(float) * t->arrSize);
  44.  
  45.     // a Foo is a twin with only one other Foo
  46.     t->myTwin = twin;
  47.     if(twin) twin->myTwin = t;
  48.  
  49.     return t;
  50. }
  51.  
  52. Foo* destroyFoo (Foo* foo)
  53. {
  54.     if (foo)
  55.     {
  56.         // we allocated the array, so we have to free it
  57.         free(foo->arr);
  58.  
  59.         // to avoid broken pointer, we need to nullify the twin pointer
  60.         if(foo->myTwin) ((Foo*)foo->myTwin)->myTwin = NULL;
  61.     }
  62.  
  63.     free(foo);
  64.  
  65.     return NULL;
  66. }
  67.  
Success #stdin #stdout 0s 2292KB
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https://ideone.com/E314bq
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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