Threaded Binary Tree in C++

#include<iostream>
#include<stdlib.h>

using namespace std;
class node
{
public:
int data;
node *lchild;
node *rchild;
int lbit;
int rbit;
};

class TBT
{
private:
node *root,*dummy;
public:
TBT()
{
root=NULL;
dummy=NULL;
}
void create(int num);
void display();
void insert(node *, node *);
};

void TBT::create(int num)
{
node *temp,*trav;
temp=new node;
temp->data=num;
temp->lbit=0;
temp->rbit=0;
if(root==NULL)
{
dummy=new node;
dummy->data=-9999;
dummy->lbit=1;
dummy->rbit=1;
dummy->rchild=dummy;
dummy->lchild=temp;
temp->lchild=dummy;
temp->rchild=dummy;
root=temp;
}
else
{
trav=root;
insert(trav,temp);
}
}

void TBT::insert(node *trav, node *temp)
{
if(temp->data<trav->data)
{
if(trav->lbit==0)
{
temp->lchild=trav->lchild;
temp->rchild=trav;
trav->lchild=temp;
trav->lbit=1;
}
else
insert(trav->lchild,temp);

}
if(temp->data>trav->data)
{
if(trav->rbit==0)
{
temp->rchild=trav->rchild;
temp->lchild=trav;
trav->rchild=temp;
trav->rbit=1;
}
else
insert(trav->rchild,temp);
}
}

void TBT::display()
{
void inorder(node *trav,node *dummy);
void preorder(node *trav,node *dummy);
void postorder(node *trav,node *dummy);

int ch;
node *trav, *trav2, *trav3;
if(root==NULL)
{
cout<<"TBT is not yet created:";
return;
}
else
{
do
{
cout<<"\n\n Enter ur choice";
cout<<"\n 1.Inorder Traversal";
cout<<"\n 2.Preorder Traversal";
cout<<"\n 3.Postorder Traversal";
cout<<"\n 4.Exit";
cin>>ch;
switch(ch)
{
case 1: cout<<"  ";
trav=root;
inorder(trav,dummy);
break;
case 2: cout<<"  ";
node *trav2;
trav2=root;
preorder(trav2,dummy);
break;
case 3: cout<<"  ";
node *trav3;
trav3=root;
postorder(trav3,dummy);
break;
case 4: exit(0);
default:cout<<"\n Wrong choice";
break;
}
}while(ch!=4);
      }
}


void preorder(node *trav,node *dummy)
{
cout<<endl;
if(trav==NULL)
{
cout<<"\n TBT Tree is empty";
}
else
{
while(trav!=dummy)
{
cout<<"\n"<<trav->data;

if(trav->lbit==1)
{
trav=trav->lchild;
}
else
{
while(trav->rbit==0 && trav->rchild!=dummy)
{
trav=trav->rchild;
}
trav=trav->rchild;
}
}}

}

void inorder(node *trav,node *dummy)
{
cout<<endl;
if(trav==NULL)
{
cout<<"\n TBT tree is empty";
}
else
{
while(trav!=dummy)
{
while(trav->lbit==1)
{
      trav=trav->lchild;
}
cout<<"\n"<<trav->data;
while(trav!=dummy)
{
if(trav->rbit==1)
{
trav=trav->rchild;
while(trav->lbit==1)
{
trav=trav->lchild;
}
cout<<trav->data<<endl;
}
else
{
while(trav->rbit==0)
{
trav=trav->rchild;
if(trav==dummy)
{
break;
}
cout<<trav->data<<endl;
}
}
}

}}

}

void postorder(node *trav,node *dummy)
{
   int i=0,a[20],n;
   if(trav==NULL)
   {
cout<<"\n TBT Tree is Empty.";
   }
   else
   {
while(trav!=dummy)
{
  a[i]=trav->data;
  i++;
  if(trav->rbit==1)
  {
trav=trav->rchild;
  }
  else
  {
     while(trav->lbit==0 && trav->lchild!=dummy)
     {
 trav=trav->lchild;
     }
     trav=trav->lchild;
  }
}
   }
   n=i;
   n--;

   for(i=n;i>=0;i--)
   {
cout<<"\n"<<a[i];
   }
}



int main()
{
TBT t;
int ch,num,i,temp;
do
{
cout<<endl<<"1. Create TBT";
cout<<endl<<"2. Display";
cout<<endl<<"3. Exit";
cout<<endl<<"Enter ur choice";
cin>>ch;
switch(ch)
{
case 1: cout<<endl<<"Enter number of nodes u want to insert";
cin>>num;
for(i=0;i<num;i++)
{
cout<<endl<<"Enter the data";
cin>>temp;
t.create(temp);
}
break;
case 2: t.display();
break;
case 3: exit(0);
default: cout<<endl<<"Wrong choice";
}
}while(ch!=3);
return 0;
}