Function parameter - pointer or reference to a pointer?

Question

void DeleteChildren(BSTNode *node)
{
    // Recurse left down the tree...
    if(node->HasLeftChild()) DeleteChildren(node->GetLeftChild());
    // Recurse right down the tree...
    if(node->HasRightChild()) DeleteChildren(node->GetRightChild());

    // Clean up the data at this node.
    node->ClearData(); // assume deletes internal data

    // Free memory used by the node itself.
    delete node;
}

// Call this from external code.
DeleteChildren(rootNode);

This function is deleting BST recursively.

I got a question about the first line, BSTNode *node , should I modify it to be BSTNode *& node ?

Answer 1

The only time you'd want to pass a pointer by reference is if you want to change what the pointer is pointing to. If you wanted to, say, set the nodes to NULL after deleting them, then you would need to pass as BSTNode*&.