Question

This method finds the largest node in a BST returns its value and deletes it. I am getting an access violation at prev->rightLink = cur->leftLink;. I am relatively unfamiliar with C++ and not able to find the cause.

int CTree::popLargest(TreeNode* tr)
{   
    int largest;
    TreeNode* prev = NULL;
    TreeNode* cur = tr;

    while (cur->rightLink != NULL)
    {
        prev = cur;
        cur = cur->rightLink;
        largest = cur->info;
        //DeleteAttemptTwo(tr, largest);//DeleteItem(largest);     
    }

    if (cur->leftLink != NULL)
    {
        prev->rightLink = cur->leftLink;
    }
    else 
    {
        prev->rightLink = NULL;
    }

    return largest;
}

Answer 1

This if and else makes little sense –

if (cur->leftLink != NULL)
{
    prev->rightLink = cur->leftLink;
}
else 
{
    prev->rightLink = NULL;
}

What you are trying to do can be done just by – prev->rightLink = cur->leftLink;

And the reason you are getting access violation on this statement is that prev is not pointing to a valid node, which is when it is NULL (as initialized).