Question

I created a class binary search tree.
but the problem is when i print the tree it crashes.
i think it can be an endless recursion in function print().

Here is my code

struct node{
node *l,*r;
int data;
};

class BinTree
{
  private:  node *root;
  public:
   BinTree(){ root=NULL; }
   void add(int a){ add_node(a,root); };
   void add_node(int a, node *rot)
   { node *curr; curr=rot;
       if(curr==NULL)
       {
           curr=new node;
           curr->data=a;
           curr->l=NULL;
           curr->r=NULL;
           return;
       }
       if(a>=curr->data)   curr=curr->r,add_node(a,curr);
       if(a<curr->data)    curr=curr->l,add_node(a,curr);
   }
   void print(){ inorder(root); }
   void inorder(node *curr)
   {
     if(curr->l!=NULL)   inorder(curr->l);
     cout<<curr->data<<" ";
     if(curr->r!=NULL)   inorder(curr->r);
   }
};

Can anyone help me?

Answer 1

Your add_node is broken. If curr is NULL, it creates a new node but it never actually adds it to the existing tree. Thus all additions you make are effectively ignored and the tree stays empty.

The inorder function dereferences curr without checking whether it is NULL, and print calls it without checking whether root is NULL. Thus, your crash most likely is caused by tryin to print out an empty tree and then dereferencing a null pointer.