Linked List

This is a discussion on Linked List within the C Programming forums, part of the General Programming Boards category; I'm still trying to insert a node at a passed index in a linked list. This is my function, it ...

  1. #1
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    Feb 2013
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    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;
          }
    }

  2. #2
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    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?

  3. #3
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    Around 8.3 light-minutes from the Sun
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    Another linked list problem.......Eternally Confuzzled - Linked List Tutorial
    Quote Originally Posted by anduril462 View Post
    Now, please, for the love of all things good and holy, think about what you're doing! Don't just run around willy-nilly, coding like a drunk two-year-old....
    Quote Originally Posted by quzah View Post
    ..... Just don't be surprised when I say you aren't using standard C anymore, and as such,are off in your own little universe that I will completely disregard.
    Warning: Some or all of my posted code may be non-standard and as such should not be used and in no case looked at.

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