Thread: A simple Tree class problem.

Can someone help me finding that why this code is not working as expected?

Code:

#include <iostream>
#include <cstdlib>
using namespace std;

struct Node
{
        int item;
        Node *left;
        Node *right;
};

class Tree
{
        Node *root;
public:
        Tree()
        {
                root = new Node;
                root->left = 0;
                root->right = 0;
                root->item = 0;
        }

        void insert(int i) { ins(i, root); }
        void inorder() { in(root); }

private:
        void ins(int i, Node *r)
        {
                if (!r)
                {
                        r = new Node;
                        r->left = r->right = 0;
                        r->item = i;
                }
                else
                {
                        if (r->item > i) ins(i, r->left);
                        else if (r->item < i) ins(i, r->right);
                }
        }
        
        void in(Node *r)
        {
                if (r)
                {
                        in(r->left);
                        cout << r->item << ' ';
                        in(r->right);
                }
        }
};

int main()
{
        Tree t;
        for (int n=1; n<=10; ++n)
        {
                t.insert(rand() % 100);
        }
        t.inorder();
        return 0;
}

without knowing what you expect it to do, no.

Originally Posted by jwenting

without knowing what you expect it to do, no.

Well I just want it to insert items in tree and then print the inserted items.

Originally Posted by Bench82

Also, its a bit pointless creating a 'zero' node in the tree's constructor

Oops! I did not realize that. Thanks.

Yeah I hope that reference to pointer may work. I'll test it and post.
Thanks guys!

It works now! Thanks everyone!

Code:

#include <iostream>
#include <cstdlib>
using namespace std;

struct Node
{
        int item;
        Node *left;
        Node *right;
};

class Tree
{
        Node *root;
public:
        Tree()
        {
                root = 0;
        }

        void insert(int i) { ins(i, &root); }
        void inorder() { in(root); }

private:
        void ins(int i, Node **p)
        {
                Node *r = *p;
                if (!r)
                {
                        r = new Node;
                        r->left = r->right = 0;
                        r->item = i;
                        *p = r;
                }
                else
                {
                        if (r->item > i) ins(i, &r->left);
                        else if (r->item < i) ins(i, &r->right);
                }
        }
        
        void in(Node *r)
        {
                if (r)
                {
                        in(r->left);
                        cout << r->item << ' ';
                        in(r->right);
                }
        }
};

int main()
{
        Tree t;
        for (int n=1; n<=100; ++n)
        {
                t.insert(n);
        }
        t.inorder();
        return 0;
}