Thread: practicing memory management

So I have a declare two structures like so

Code:

struct X
{
   struct Y *y;
};

struct Y
{
    char *A
    char *B
};

in main this what I have done

Code:

int main()
{
    int size = 100;
    struct X **x = createX(size);

   if(x == NULL || (*x)->y == NULL)
   {
      printf("Critical Error! ran out of memory.");
      return EXIT_FAILURE;
   }

    freeMem(x);
}

I call createX so I can allocate some memory.

Code:

Struct X ** createX(int size)
{
  struct X **x = malloc(size * sizeof(struct X *));

  if(x == NULL) return NULL;

  (*x)->y = malloc(size * sizeOf((*x)->y));

  if((*x)->y == NULL)
  {
     free(x); //We free because we allocated n pointers
     return NULL;
  }
 
  int i;

  for(i = 0; i < 10; i++)    
  {
        x[i] = malloc(sizeof(struct X));

        if(x[i] == NULL) // If we dont't have enough memory for the pointers to point to a struct X
        {
            free((*x)->y);
            free(x);
            return NULL;
        }
  }


    return x;
}

Call freeMem to deallocate

Code:

    void freeMem(Struct X **x)
    {
        int i;

        for(i = 0; i < 10; i++)
        {
            if(x[i] != NULL) // we dont want to free(NULL)
           {
               free(x[i]); // free allocated structure
           }
        }


        if(players != NULL)
        {
           free((*x)->y); // free the pointer to struct Y
           free(x); // free up all the pointers
        }
     }

That's it. Is there anything I did wrong or forgot to do or even added stuff that I didn't need to?

Are you sure it is overwriting it? the first thing I did was create an array of pointers to a struct called X(Note that this doesn't allocate memory for the structure pointer y inside the struct X and the array of pointers have nothing to point to at moment). Then we allocate memory for the struct pointer y. Then we allocate 10 structs and have an array point to them. That is the gist of what createX is doing. Also, I did not really do this with a demo in mind. The point of this was to ask if I was allocating and deallocating memory correctly as that is something you do quite often in c when you are working with pointers.

Edit: opps now I notice that the size is 100 and the conditional of each for loop is index < 10 when it should have been index < 100 my mistake for both for loops.