Create a Binary Tree, Traverse Using Inorder, Preorder & Postorder

Write a Program in C to Create a Binary Tree, Traverse Using Inorder, Preorder & Postorder

　
#include<stdio.h>
#include<conio.h>
struct node
{
int data;
struct node *right, *left;
}*root,*p,*q;
struct node *make(int y)
{
struct node *newnode;
newnode=(struct node *)malloc(sizeof(struct node));
newnode->data=y;
newnode->right=newnode->left=NULL;
return(newnode);
}
void left(struct node *r,int x)
{
if(r->left!=NULL)
printf("\n Invalid !");
else
r->left=make(x);
}
void right(struct node *r,int x)
{
if(r->right!=NULL)
printf("\n Invalid !");
else
r->right=make(x);
}
void inorder(struct node *r)
{
if(r!=NULL)
{
inorder(r->left);
printf("\t %d",r->data);
inorder(r->right);
}
}
void preorder(struct node *r)
{
if(r!=NULL)
{
printf("\t %d",r->data);
preorder(r->left);
preorder(r->right);
}
}
void postorder(struct node *r)
{
if(r!=NULL)
{
postorder(r->left);
postorder(r->right);
printf("\t %d",r->data);
}
}
void create()
{
int no;
char choice='y';
printf("\nEnter the root:");
scanf("%d",&no);
root=make(no);
p=root;
while(choice=='y'||choice=='Y')
{
printf("\nEnter number:");
scanf("%d",&no);
if(no==-1)
break;
p=root;
q=root;
while(no!=p->data && q!=NULL)
{
p=q;
if(no<p->data)
q=p->left;
else
q=p->right;
}
if(no<p->data)
{
printf("Left branch of %d is %d\n",p->data,no);
left(p,no);
}
else
{
right(p,no);
printf("Right Branch of %d is %d\n",p->data,no);
}
printf("\t\t\t\t\t\t\t\tContinue ? ");
scanf(" %c",&choice);
}
}
void main()
{
int no,action;
clrscr();
while(1)
{
printf("\n\n1) Create\n");
printf("2) Inorder Traversal\n");
printf("3) Preorder Traversal\n");
printf("4) Postorder Traversal\n");
printf("5) Exit\n");
printf("Enter choice : ");
scanf("%d",&action);
switch(action)
{
case 1:
create();
break;
case 2:
printf("\n\nInorder Traversal is \n\t\t\t");
inorder(root);
break;
case 3:
printf("\n\nPreorder Traversal is \n\t\t\t");
preorder(root);
break;
case 4:
printf("\n\nPostorder Traversal is \n\t\t\t");
postorder(root);
break;
case 5:
exit();
break;
}
getch();
}
}