Tree Traversing

//C++ Program TO Process Tree Traversing

#include<iostream.h>

#include<conio.h>

#define NULL 0

struct node

{

 struct node *left;

 int data;

 struct node *right;

};

class tree

{

 struct node *p,*t,*root;

 public:

            tree()

            {

             root=new node;

             root=NULL;

             }

             struct node *creation(struct node *p,int x);

             void inorder(struct node *p);

             void preorder(struct node *p);

             void postorder(struct node *p);

};

struct node *tree::creation(struct node *p,int x)

{

 if(p==NULL)

 {

  t=new node;

  t->data=x;

  t->left=NULL;

  t->right=NULL;

  p=t;

  }

 else if(x<p->data) p->left=creation(p->left,x);

  else p->right=creation(p->right,x);

 return p;

 }

 void tree::preorder(struct node *p)

 {

  if(p!=NULL)

  {

   cout<<"  "<<p->data;

   preorder(p->left);

   preorder(p->right);

   }

  }

 void tree::inorder(struct node *p)

 {

  if(p!=NULL)

  {

   inorder(p->left);

   cout<<"  "<<p->data;

   inorder(p->right);

   }

  }

 void tree::postorder(struct node *p)

 {

  if(p!=NULL)

  {

   postorder(p->left);

   postorder(p->right);

   cout<<"  "<<p->data;

   }

  }

void main()

{

 clrscr();

 tree t;

 int c,x;

 struct node *r;

 cout<<"\n\t\t TREE TRAVERSAL";

 cout<<"\n\t\t ~~~~~~~~~~~~~~";

 cout<<"\n";

 cout<<"\n";

 cout<<"\t * Enter The Root Value: " ;

 cin>>x;

 r=t.creation(NULL,x);

 do

 {

  cout<<"\n";

  cout<<"\t Enter The Number : ";

  cin>>x;

  t.creation(r,x);

  cout<<"\n";

  cout<<" Press 1 To Continue : ";

  cin>>c;

  }while(c==1);

 cout<<"\n";

 cout<<"\t\t Traversals \n";

 cout<<"\t\t ~~~~~~~~~~ \n";

 cout<<"\n";

 cout<<"\t Preorder : ";

 t.preorder(r);

 cout<<"\n";

 cout<<"\t Inorder  : ";

 t.inorder(r);

 cout<<"\n";

 cout<<"\t Postorder: ";

 t.postorder(r);

 getch();

 }