Thread: Linked List

I'm still trying to insert a node at a passed index in a linked list. This is my function, it doesn't work but i feel like it's close. Any pointers appreciated

Code:

void llAddAtIndex(LinkedList** ll, char* value, int index) {

  LinkedList* newNode = (LinkedList*)malloc(sizeof(LinkedList));
  newNode->value = value;
  LinkedList* prevNode = *ll;


  for(int i = 0; i < index; i++){
      prevNode = newNode;
    newNode = newNode->next;
  }
    if (prevNode) {
      prevNode->next = newNode;
      newNode->next = newNode;
    } else { 
        value = *newNode;
        newNode->next = *newNode;
      }
}

Think about what you're doing here:

Code:

  for(int i = 0; i < index; i++){
     prevNode = newNode;
     newNode = newNode->next;
  }

Suppose for example that the index value is 10. How useful is it to do
"prevNode = newNode" 10 times? (Or even once for that matter.)

And having done that, when will the if condition on the next line

Code:

  if (prevNode) {

ever fail?

Also, there are several special cases that you must consider:
1. What if ll is an empty list and index is 0?
2. What if ll is NOT an empty list and index is 0?
3. What if index is greater than the number of nodes in ll?