Insert Node recursively in BTree using C++ - c++

Question

Creating a template class to insert data recursively in BTree. The code gives segmentation error, I have included the getter and setter functions in header file, not sure where it is going wrong, please help to suggest, if I remove the check on Node->right==NULL, then the code works fine, but in that case I am unable to add recursion.
template <class S>
class STree
{
public:
// Constructors
STree()
{root = NULL; size=0;}
STree(S part)
{root = new BTNode<S>(part); size=0;}
// Destructor
~STree(){};
void insert(S part)
{
if (root == NULL)
{
root = new BTNode<S>(part);
cout<< "\n from root " << root->get_data();
}
else
{add(root,part);}
size++;
}
void add(BTNode<S>* node, S part)
{
S part2 = node->get_data();
cout << "part "<< part;
cout<< "part2 "<< node->get_data();
if( part == part2)
{node->set_data(part);}
else if (part > part2)
{
if (node->get_right()== NULL) //if I remove this check the segmentation error goes away
{node->set_right(new BTNode<S>(part)); cout<< "from right "<< node->right->get_data();}
else
{add(node->get_right(),part);} //If I remove the if statement above the recursion won't work
}
else
{
if (node->get_left()==NULL)
{ node->set_left(new BTNode<S>(part));}
else
{add(node->get_left(),part);}
}
}
private:
BTNode<S>* root;
BTNode<S>* current;
int size;
};
#endif
int main()
{
STree<int> trees;
trees.insert(10);
trees.insert(20);
trees.insert(30);
trees.insert(40);
return 0;
}

Answer 1

BS part2 = node->get_data() will access nullptr every time you insert. When implementing recursion, always take care of the base case first.
void add(BTNode<BS>* node, BS part)
{
if (part < node->get_data() && node->get_left() == nullptr)
node->set_left(new BTNode<BS>(part));
else if (part > node->get_data() && node->get_right() == nullptr)
node->set_right(new BTNode<BS>(part));
if (node->get_data() == part)
return;
else
{
if (part < node->get_data())
add(node->get_left(), part);
else
add(node->get_right(), part);
}
}