Realloc in C for structs containing dynamic array of structs - c

Question

Issues with reallocing the items list. I am trying to add items into the testList structs items, but i am getting memory address errors when trying to add or print the values for the individual ListItems. Any help would be greatly appreciated.
struct ListItems
{
int id;
int name;
};
struct testList
{
struct ListItems** items;
int count;
int size;
};
struct Test
{
struct testList* list;
};
void printArray(struct testList* list)
{
for (int i = 0; i < list->count; i++)
{
printf("id=%i, name= %i \n", list->items[i]->id, list->items[i]->name);
fflush(stdout);
}
printf("printing accomplished \n");
fflush(stdout);
}
void growArray(struct testList* list, struct ListItems* item)
{
int size = list->size;
list->items[list->count++] = item;
struct ListItems** user_array = list->items;
//printf("array count %i, array size %i \n", list->count, size);
if (list->size == list->count)
{
struct ListItems* temp = realloc(*user_array, (size * 2) * sizeof (struct ListItems));
if (temp == NULL)
{
printf("it's all falling apart! \n");
}
else
{
*user_array = temp;
list->size = size * 2;
}
}
}
/*
*
*/
int main(int argc, char** argv)
{
struct Test* test = (struct Test*) malloc(sizeof (struct Test));
test->list = (struct testList*) malloc(sizeof (struct testList));
test->list->count = 0;
test->list->size = 1;
test->list->items = (struct ListItems**) malloc(sizeof (struct ListItems*));
for (int i = 0; i < 32; i++)
{
struct ListItems* item = (struct ListItems*) malloc(sizeof (struct ListItems));
item->id = i;
item->name = i;
growArray(test->list, item);
}
printArray(test->list);
for (int j = 0; j < sizeof (test->list->items); j++)
{
free(test->list->items[j]);
}
free(test->list->items);
free(test->list);
free(test);
}

Answer 1

The problem starts with the declaration of struct testList. A pointer to an array of items should have just one *:
struct testList
{
struct ListItems* items; // Changed from pointer-to-pointer
int count;
int size;
};
This will force some other changes in the code.

Answer 2

Your growArray() needs to update list->items. In current code, it will point forever to an 1-element sized area only.
EDIT:
your realloc() allocates for sizeof (struct ListItems)) but pointer holds pointers, not elements.
I would write:
void growArray(struct testList* list, struct ListItems* item)
{
if (list->size <= list->count) {
size_t new_size = 2 * list->size;
struct ListItems** temp = realloc(list->items, new_size * sizeof temp[0]);
assert(temp);
list->size = new_size;
list->items = temp;
}
list->items[list->count] = item;
++list->count;
}
With this, you do not need the initial list->items = malloc(...) in main() but can assign NULL.
EDIT:
for (int j = 0; j < sizeof (test->list->items); j++)
does not make sense; you probably want to j < test->list->count.