Thread: Help free structs and pointer.

This I've got to see.

Code:

LIST_ELEM *add(LIST_ELEM *pHead,char type[],char name[], char title[], int year, double price, int size){

	LIST_ELEM *new_elem = malloc(sizeof(LIST_ELEM));

	strcpy(new_elem->type, type);
	strcpy(new_elem->name,name);
	strcpy(new_elem->title, title);

	new_elem->year = year;
	new_elem->price = price;
	new_elem->size = size;
	new_elem->pNext = pHead;

	return new_elem;

}

lol i think you helped me out on this the other day =)

Oh, you're returning the new head instead of changing the parameter.

Well ... why not do that here? Instead of returning void, return a LIST_ELEM* that's the new head of the list.

so I return pHead but that didn't solve my whole removal issue. Going back to the whole *ptr and **ptr deal, would I still have to do that?

HAH HAH finally getting somewhere. So I've got the case were the list is 1 element, and the element is the first element to work. But I can't get the last case to work, where the element is somewhere in the middle of the list. Can you spot where I'm going wrong? i get a seg fault. when i try this.

Code:

 else if( i == loc){
		LIST_ELEM *ptrB4 = nodeB4(pHead,loc);
		tmpPtr = ptr;
		LIST_ELEM *ptrAfter = (tmpPtr->pNext);
		ptrB4->pNext = ptrAfter;
		free(tmpPtr);
		break;
		}

Not really; you've got two choices:
Option 1: return void, change the parameter

Code:

void removePtr(LIST_ELEM **pHead, int loc) {
    LIST_ELEM *prevPtr, *nextPtr, *tempPtr;
    int size = sizeOf(*pHead);

    if (loc == 0) {
        if (size == 0) return; //already empty
        prevPtr = (*pHead)->next;
        free(*pHead);
        *pHead = prevPtr;
        return;
    }

    if (size < loc) return; //can't delete element that doesn't exist

    //if we're still here then walk to the element and delete it
    tempPtr = *pHead;
    for (int i = 0; i < loc; i++) {
        tempPtr = tempPtr->next;
    }
    prevPtr = nodeB4(*pHead, loc); //if we didn't have the function, we'd walk prevPtr with tempPtr
    nextPtr = tempPtr->next;
    prevPtr->next = nextPtr;
    free(tempPtr);
    return;
}

Option 2, return the head of the list (consistent with your add)

Code:

LIST_ELEM *removePtr(LIST_ELEM *pHead, int loc) {
    LIST_ELEM *prevPtr, *nextPtr, *tempPtr;
    int size = sizeOf(pHead);

    if (loc == 0) {
        if (size == 0) return NULL; //already empty
        prevPtr = pHead->next;
        free(pHead);
        pHead = prevPtr;
        return pHead;
    }

    if (size < loc) return pHead; //can't delete element that doesn't exist

    //if we're still here then walk to the element and delete it
    tempPtr = pHead;
    for (int i = 0; i < loc; i++) {
        tempPtr = tempPtr->next;
    }
    prevPtr = nodeB4(pHead, loc); //if we didn't have the function, we'd walk prevPtr with tempPtr
    nextPtr = tempPtr->next;
    prevPtr->next = nextPtr;
    free(tempPtr);
    return pHead;
}

I've assumed you still don't want loc==0 to kill the whole list. EDIT: Also I haven't tested it, or even compiled it, so caveat lector.

ah hah hah thnx again tabstop. Its workin now. (sigh) what a work out.