Inorder traversal for binary search tree, shows some errors - c

Question

This is the function which I am using for BST inorder Traversal
void inOrder(struct node* root)
{
if(root==NULL)
{
return;
}
inOrder(root->left);
printf("Key:%d,Pointer:%p\n",root->key,root);
inOrder(root->right);
}
The structure for the same is
struct node{
int key;
struct node *left,*right;
};
When I run the function I get two 0 extra elements for the following inserts:
root=insert(root,7);
insert(root,4);
insert(root,10);
insert(root,3);
insert(root,5);
insert(root,1);
insert(root,2);
insert(root,0);
insert(root,8);
insert(root,14);
insert(root,6);
insert(root,9);
insert(root,16);
insert(root,12);
insert(root,15);
insert(root,17);
inOrder(root);printf("\n");
And the insert function is given below:
struct node *insert(struct node * root,int ele)
{
struct node *temp=newNode(ele);
struct node *tree=root;
struct node *saver;
if(root==NULL)
{
root=temp;
}
else
{
while(tree!=NULL)
{
saver=tree;
if(ele<tree->key)
tree=tree->left;
else
tree=tree->right;
}
if(ele<saver->key)
{
saver->left=temp;
}
else
{
saver->right=temp;
}
}
return saver;
}
The output shows two 0s apart from the main elements, which I added. I have recently learned the Binary-Search-Tree, and I tried to implement it, Can someone please help me rectify this error. Thank you in advance

Answer 1

in insert
if(root==NULL)
{root=temp;
}
must be
if(root==NULL)
{
saver=temp;
}
because you return saver (not initialized in your version)
I suppose also in your main the code is not what you give but something like
struct node * root = NULL;
root=insert(root,7);
insert(root,4);
...
If I define newNode like that :
struct node * newNode(int ele)
{
struct node * r = malloc(sizeof(struct node));
r->key = ele;
r->left = r->right = NULL;
return r;
}
and I do the other changes :
pi#raspberrypi:/tmp $ gcc -g -pedantic -Wextra n.c
pi#raspberrypi:/tmp $ ./a.out
Key:0,Pointer:0xf04078
Key:1,Pointer:0xf04058
Key:2,Pointer:0xf04068
Key:3,Pointer:0xf04038
Key:4,Pointer:0xf04018
Key:5,Pointer:0xf04048
Key:6,Pointer:0xf040a8
Key:7,Pointer:0xf04008
Key:8,Pointer:0xf04088
Key:9,Pointer:0xf040b8
Key:10,Pointer:0xf04028
Key:12,Pointer:0xf040d8
Key:14,Pointer:0xf04098
Key:15,Pointer:0xf040e8
Key:16,Pointer:0xf040c8
Key:17,Pointer:0xf040f8
The full code is :
#include <stdio.h>
#include <stdlib.h>
struct node{
int key;
struct node *left,*right;
};
void inOrder(struct node* root)
{
if(root==NULL)
{return;}
inOrder(root->left);
printf("Key:%d,Pointer:%p\n",root->key,root);
inOrder(root->right);
}
struct node * newNode(int ele)
{
struct node * r = malloc(sizeof(struct node));
r->key = ele;
r->left = r->right = NULL;
return r;
}
struct node *insert(struct node * root,int ele)
{
struct node *temp=newNode(ele);
struct node *tree=root;
struct node *saver;
if(root==NULL)
{
saver=temp;
}
else
{
while(tree!=NULL)
{
saver=tree;
if(ele<tree->key)
tree=tree->left;
else
tree=tree->right;
}
if(ele<saver->key)
{
saver->left=temp;
}
else
{
saver->right=temp;
}
}
return saver;
}
int main()
{
struct node * root = NULL;
root=insert(root,7);
insert(root,4);
insert(root,10);
insert(root,3);
insert(root,5);
insert(root,1);
insert(root,2);
insert(root,0);
insert(root,8);
insert(root,14);
insert(root,6);
insert(root,9);
insert(root,16);
insert(root,12);
insert(root,15);
insert(root,17);
inOrder(root);printf("\n");
}