Segmentation Fault coming “Insertion in Binary Search tree.” #

Question

I am writing a function to insert a node in BST ,but getting segmentation fault.

    /*
    Node is defined as 

   typedef struct node
   {
     int data;
     node * left;
     node * right;
  }node;

   */

    node * findPos(node * tree, int value){
       if(tree -> data > value){
             return findPos(tree -> left, value);
        }
       else if (tree -> data < value){
            return findPos(tree -> right, value);
       }

        return tree;
   }

   node * addNode(int value){

       struct node * temp =(struct node *)malloc(sizeof(struct node));
       temp->data = value;
       temp->left = NULL;
       temp -> right = NULL;
       return temp;
    }
    node * insert(node * root, int value)
    {
       node * ptr = root;

       if(ptr == NULL)
          return addNode(value);

        else if(ptr -> data > value){
            ptr->left = findPos(ptr -> left, value);
}

      else if(ptr -> data < value){
          ptr->right = findPos(ptr -> right, value);
       }  


       return root;
    }

i am not able to understand which illegal memory i am trying to access which is giving this error. Please help me with this. Thanks in advance :)

Answer 1

There are two issues here:

1. findPos should handle the case in which tree is NULL.

2. insert should not recursively call findPos. Instead it should recursively call insert. Something like this (haven't tested it):

    node * insert(node * root, int value) { node * ptr = root; if(ptr == NULL) return addNode(value); else if(ptr -> data > value) { return insert(ptr -> left, value); } else if(ptr -> data < value) { return insert(ptr -> right, value); } else return root; } 

Answer 2

Thanks for the help guys!!! got the program working

   /*
    Node is defined as 

  typedef struct node
  {
     int data;
     node * left;
     node * right;
  }node;

*/

   node * addNode(int value){

    struct node * temp =(struct node *)malloc(sizeof(struct node));
    temp->data = value;
    temp->left = NULL;
    temp -> right = NULL;
    return temp;
  }
  node * insert(node * root, int value)
  {
      node * ptr = root;

     if(ptr == NULL)
       return addNode(value);

     else if(ptr -> data > value){
       ptr->left =  insert(ptr -> left, value);
     }

     else if(ptr -> data < value){
        ptr->right =  insert(ptr -> right, value);
     }  


    return root;
   }