Question

I’m getting a segmentation fault when I try to create a new Node object with the pointer variable *temp in line 15 below. I’m still pretty new to c++ and how double pointers work, especially when used in combination with &. Thanks for any help.

void bst::insert(int n) {
    Node **temp;
    Node *r, *parent;
    // Tree is empty
    if (root == NULL) {
        root = new Node;
        root->parent = NULL;
        root->value = n;
        root->left = NULL;
        root->right = NULL;
        root->isBlack = true;
    } else {
        r = root;
        // Create a node with the given value, n
        (*temp) = new Node;
        (*temp)->value = n;
        (*temp)->left = NULL;
        (*temp)->right = NULL;
        (*temp)->isBlack = false;

Answer 1

The variable temp is not initialized. Therefore, trying to dereference temp will fail, as there is no value to dereference. If you really need a pointer to a pointer, you could just declare the single pointer and use the & operator to get the double pointer.