linked list free

[dusky swift]

How to free the memory allocated to a linked list and all its elements?

[scenic vault]

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[dusky swift]

Sending my current code in a sec

typedef struct _list {
    element* first;
    int count;
} list;

typedef struct _element {
    uint32_t year;
    uint64_t isbn;
    char author[MAX_STR];
    char title[MAX_STR];
    struct _element *next;
} element;

element* insert_at_begin(element* first, element* new_elem) {
    new_elem -> next = first;
    new_elem;
}

element *construct_element(char* title, char* author, uint32_t year, uint64_t isbn) {
    element *new_elem = malloc(sizeof(new_elem));

    strncpy(new_elem -> title, title, MAX_STR);
    new_elem -> title = title;
    strncpy(new_elem -> author, author, MAX_STR);
    new_elem -> author = author;
    new_elem -> year = year;
    new_elem -> isbn = isbn;

    new_elem -> next = NULL;
}

void free_list(list* BuecherListe) {
    element *current_elem = BuecherListe -> first;
    
}

I was thinking of creating a current_element, which is going to be set to the first element of the list, and then basically just loop through the whole list, while freeing

Is this way of thinking going in the right direction?

[deep flower]

yea, i think that's right, although you'll probably want to free the list starting from the end of it

a linked list structurally is like:

{item, ptr}
        |   (a)
        v
        {item, ptr}
                |   (b)
                v
                {item, ptr}

if you free (a) first which would free the second {item, ptr}, you won't be able to access (b)

[dusky swift]

oh I get it

[deep flower]

so you'd want to free (b) first, then (a), then the first one

[dusky swift]

but then I need to create a new variable/pointer first right

[silk spruce]

Or store the pointer to (b) before you free (a)

[dusky swift]

which is going to point to my last element

[deep flower]

yea i was about to say that, raccoon is right

you could also change the pointer of the first to point to the pointer that the one you're freeing is pointing to

that's prolly a cheaper operation too

[dusky swift]

so like creating a temporary pointer for my next element?

and while im looping, always making that temporary pointer point to my next element

as long as it is not NULL

[deep flower]

or something like

while (head->next != NULL) {
  // store head.next to prepare to free it
  element *next = head->next;
  // move head.next.next to head.next, so that pointer is not lost when head.next is freed
  head->next = head->next->next;
  // finally free what head->next used to point to
  free(next);
}

[deep flower]

yea exactly like that

[dusky swift]

thanks!

[deep flower]

i believe this should work ? unless i'm being dumb lol

[scenic vault]

@dusky swift Has your question been resolved? If so, type !solved :)

[dusky swift]

I did it a little different but should hopefully work

checking it now

Ok so looks like there are no memory problems

but the other functions are wrong

!solved