Member Avatar for MiTiM

I want to create binary tree. With this program I wrote I have some problems. It seems the element I added to the tree is always added to the root place! Adding never happens to the left or the right subtree. This thing is prooved by result I always get when I add a new element to the tree -it's always just printing message "We are adding to the root or it's a new leaf!".
Because this part of the program is doing by a recursive procedure push_in_tree I gues there is a problem, but I can't find it.I'm using win7 (C-free professional 5.0).
Thanks.

/*binary tree*/ #include <stdio.h> #define ERR_FLAG 1 struct node { int id; struct node *left; struct node *right; }; typedef struct node EL; EL *root; EL *current; void error_exit(char *str); void read_node(EL *current); void push_in_tree(EL *new_ptr, EL *root); void print_node(EL *current); void visiting_nodes(EL *root); int main() { int ch; root = NULL; do { if ((current =(EL *)malloc(sizeof(EL))) == NULL) error_exit("malloc failed"); else { current->left = NULL; current->right = NULL; current->id = 0; } read_node(current); push_in_tree(current, root); printf("Is there any more nodes (yes/no)\n"); rewind(stdin); } while ((ch=toupper(getchar())) !='N'); visiting_nodes(root); printf("**All elements are visited**"); } void error_exit(char *str) { printf("%s\n", str); exit(ERR_FLAG); } void read_node(EL *current) { printf("Please enter the id: "); scanf("%d", &(current->id)); } void push_in_tree(EL *new_ptr, EL *root) { if (root == NULL) { printf("We are adding to the root or it's a new leaf\n"); root = new_ptr; root->left= NULL; root->right= NULL; } else if (new_ptr->id < root->id) { push_in_tree(new_ptr, root->left); printf("We are going left\n"); } else { push_in_tree(new_ptr, root->right); printf("We are going right\n"); } } void print_node(EL *current) { printf("Current number is: %d\n", current->id); } void visiting_nodes(EL *root) { if (root != NULL) { visiting_nodes(root->left); printf("Press <enter> for printing next node"); getchar(); rewind(stdin); print_node(root); visiting_nodes(root->right); } }
  • 2 Contributors
  • 3 Replies
  • 309 Views
  • 19 Hours Discussion Span
  • Latest Post Latest Post by MiTiM
Member Avatar for MiTiM

OOPS!These lines are standing reverse:
74 and 75 should be:

 push_in_tree(new_ptr, root->left); printf("We are going left\n");

and 79 and 80 too should be:

 push_in_tree(new_ptr, root->right); printf("We are going right\n");

Still needing help.Thanks.

Member Avatar for deceptikon

Your push_in_tree() function has no way of telling the caller what changed. Consider this:

EL *push_in_tree(EL *new_ptr, EL *root) { if (root == NULL) { root = new_ptr; } else if (new_ptr->id < root->id) { root->left = push_in_tree(new_ptr, root->left); } else { root->right = push_in_tree(new_ptr, root->right); } return root; }

Then it would be called like so:

root = push_in_tree(current, root);

This ensures that at all levels of recursion, you can propagate changes back up the tree.

Member Avatar for MiTiM

Thanks Deceptikon! You were very quick. Now program really works. Once more: thanks!

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.