C Program for Binary Search Tree Creation and Traversals

#include <stdlib.h>
typedef struct tnode
{
int data;
struct tnode *right,*left;
}TNODE;
 
TNODE *CreateBST(TNODE *, int);
void Inorder(TNODE *);
void Preorder(TNODE *);
void Postorder(TNODE *);
main()
{
TNODE *root=NULL;		 /* Main Program */
int opn,elem,n,i;
do
{
clrscr();
printf("\n ### Binary Search Tree Operations ### \n\n");
printf("\n Press 1-Creation of BST");
printf("\n       2-Traverse in Inorder");
printf("\n       3-Traverse in Preorder");
printf("\n       4-Traverse in Postorder");
printf("\n       5-Exit\n");
printf("\n       Your option ? ");
scanf("%d",&opn);
switch(opn)
{
case 1: root=NULL;
printf("\n\nBST for How Many Nodes ?");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
printf("\nRead the Data for Node %d ?",i);
scanf("%d",&elem);
root=CreateBST(root,elem);
}
printf("\nBST with %d nodes is ready to Use!!\n",n);
break;
case 2: printf("\n BST Traversal in INORDER \n");
Inorder(root); break;
case 3: printf("\n BST Traversal in PREORDER \n");
Preorder(root); break;
case 4: printf("\n BST Traversal in POSTORDER \n");
Postorder(root); break;
case 5: printf("\n\n Terminating \n\n"); break;
default: printf("\n\nInvalid Option !!! Try Again !! \n\n");
break;
}
printf("\n\n\n\n  Press a Key to Continue . . . ");
getch();
}while(opn != 5);
}
TNODE *CreateBST(TNODE *root, int elem)
{
if(root == NULL)
{
root=(TNODE *)malloc(sizeof(TNODE));
root->left= root->right = NULL;
root->data=elem;
return root;
}
else
{
if( elem < root->data )
root->left=CreateBST(root->left,elem);
else
if( elem > root->data )
root->right=CreateBST(root->right,elem);
else
printf(" Duplicate Element !! Not Allowed !!!");
 
return(root);
}
}
void Inorder(TNODE *root)
{
if( root != NULL)
{
Inorder(root->left);
printf(" %d ",root->data);
Inorder(root->right);
}
}
 
void Preorder(TNODE *root)
{
if( root != NULL)
{
printf(" %d ",root->data);
Preorder(root->left);
Preorder(root->right);
}
}
 
void Postorder(TNODE *root)
{
if( root != NULL)
{
Postorder(root->left);
Postorder(root->right);
printf(" %d ",root->data);
}
}