C++ Struct Pointer Segfault

Question

First, thanks in advance for all of you who respond to this post.

Second, I\'ve looked through all other posts and couldn\'t find anything that helped me (my apologies,

Answer 1

The most likely issue here is that you cannot use Insert to "jump start" your list: if the head is NULL to start with, the loop is going to fail right away. Moreover, on the first insertion you wouldn't be able to assign the head.

To fix this problem, change the first parameter from Node *head to Node **pHead, pass a pointer to the head pointer, and add an extra level of dereference to the code of your Insert function:

Node* Insert(Node **pHead, int data)
{
    while(*pHead != NULL){
        pHead = &((*pHead)->next);
    }
    Node *last = new Node();
    last -> data = data;
    last -> next = NULL;
    *pHead = last;
    return last;
}

Note that this approach is going to work even if you pass a pointer to Node pointer that is set to NULL:

Node *head = NULL;
Insert(&head, 1);
Insert(&head, 2);
Insert(&head, 3);