Binary search tree

[KAWALMEET-SINGH]

#include<stdio.h>
#include<stdlib.h>
#include<malloc.h>

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

struct node* CN(int data)
{
struct node n;
n=(struct node)malloc(sizeof(struct node));
n->data=data;
n->l=NULL;
n->r=NULL;
return n;
}
void preorder(struct node *root)
{
if(root!=NULL)
{
printf("%d",root->data);
preorder(root->l);
preorder(root->r);

}

}

void postorder(struct node *root)
{
if(root!=NULL)
{
postorder(root->l);
postorder(root->r);
printf("%d",root->data);

}

}

void inorder(struct node *root)
{
if(root!=NULL)
{
inorder(root->l);
printf("%d",root->data);
inorder(root->r);

}

}

int isBST(struct node* root){
static struct node *prev = NULL;
if(root!=NULL){
if(!isBST(root->l)){
return 0;
}
if(prev!=NULL && root->data <= prev->data){
return 0;
}
prev = root;
return isBST(root->r);
}
else{
return 1;
}
}

struct node * searchIter(struct node* root, int key){
while(root!=NULL){
if(key == root->data){
return root;
}
else if(keydata){
root = root->l;
}
else{
root = root->r;
}
}
return NULL;
}

void insert(struct node *root, int key){
struct node prev = NULL;
while(root!=NULL){
prev = root;
if(key==root->data){
printf("Cannot insert %d, already in BST", key);
return;
}
else if(keydata){
root = root->l;
}
else{
root = root->r;
}
}
struct node new = CN(key);
if(keydata){
prev->l= new;
}
else{
prev->r= new;
}

}

int main(){

struct node *p = CN(5);
 struct node *q = CN(6);
  struct node *r = CN(4);
  p->l=r;
  p->r=q;
insert(p,15);
insert(p,14);
insert(p,2);
insert(p,8);
insert(p,69);

preorder(p);
printf("\n");
inorder(p);
 printf("\n");
postorder(p);
 printf("\n");
if(isBST(p))
{
    printf(" binary search tree");
}
 printf("\n \n kawalmeet singh \n \n  ");

}