Help free structs and pointer.

hm you kind of lost me there.
So I have this list LIST_ELEM which holds a bunch of structs

pHead <-strct1<-strct2

and when I remove it i want it to look like

pHead<-struct2

or in the first case

pHead<-strct1

remove returns

pHead


but i'm not getting anything like that, I'm getting my original list when print it out, or find the size

so if I call a remove on my list which holds 1 item, shouldn't the size of the list after the remove return 0?

So run the following code and play "spot the parallel":

Code:

---

void func1(int bob) {
    bob = 6;
}

void func2(int *bob) {
    bob = NULL;
}

int main(void) {
    int i = 11;
    int *iptr = &i;
    func1(i);
    printf("%d\n", i);
    func2(iptr);
    if (iptr == NULL) printf("Variable successfully removed.\n");
    printf("%p\n", iptr);
    return 0;
}

---

11 and an address is returned.

so i basically can't set something to null and say it was removed.

Even though you pass in a pointer to the function, that means you can only change the value of what is pointed to, not the value of the pointer itself (that's just a copy). So if you want to change the value of the pointer, which it seems like you do, you'll have to add an extra *.

So if:

LIST_ELEM *ptr = pHead;

and I want to free the actual item at *ptr

i would have to use

free(**ptr)? doesn't that return an invalid type error?

No you would have to use

Code:

---

void removePtr(LIST_ELEM **pHead, int loc)

---

and adjust accordingly.

Man that would make it more difficult for me.

so taking in a *pHead and then setting equal to say

Code:

---

LIST_ELEM **ptr = pHead

---

You could do that but you're back where you started -- pHead wouldn't change just because you changed ptr.

I'm starting to worry a little bit -- all the list functions require a elem** to work (creating, adding, deleting, ...)

EDIT: And for that matter, it's not as though the change is hard: do a search-and-destroy turning pHead to *pHead everywhere in the function and you're done!

LOL you're beginning to worry me now. I've been using (LIST_ELEM *pHead) for my add, print, and find methods.

Well, okay, print just takes one star. Find could take one * if you're not trying to change the list. But if you add something to the front of the list and try to change pHead = just_created_element, that won't work.

so my program is a fluke since I use one * for add, and sizeOf returns the right size after adding in an element.

Are you in a special case where you are always adding at the end or something?

always adding to the front