Circular Queue program in Data Structure

#include<iostream.h>

#include<conio.h>

classsqueue

{

private:

squeue *prev,*next;

int data;

public :

void add(int);

void display(void);

void remove(void);

};

squeue *front;

squeue *rear;

voidsqueue::add(intnum)

{

squeue *temp;

if(front==NULL && rear==NULL)

 {

front=rear=new squeue;

front->prev=NULL;

front->next=NULL;

front->data=num;

 }

else

 {

temp=front;

rear->next=new squeue;

rear->next->data=num;

rear->next->prev=rear;

rear->next->next=front;

rear=rear->next;

front->prev=rear;

 }}

voidsqueue::display()

{

squeue *q=front;

if(front==NULL && rear==NULL)

{

cout<<"no queue";

}

else

{do

{

cout<<q->data<<"\t";

q=q->next;

}

while(q!=rear->next);

}}

voidsqueue::remove()

{

squeue *temp=front;

front=front->next;

front->prev=NULL;

cout<<endl<<temp->data<<" is removed\n";

delete(temp);

display();

}

void main()

{

clrscr();

squeue s;

char c='y';

intopt,num;

while(c=='y')

{

cout<<"\n 1.add \n 2. display  \nenter option: ";

cin>>opt;

switch(opt)

{

case 1:

cout<<"enter number in queue:";

cin>>num;

s.add(num);

cout<<"\ndo you want to continue:";

break;

case 2:

s.display();

cout<<"\ndo you want to continue:";

break;

case 3:

s.remove();

cout<<"\ndo you want to continue:";

break;

default:

cout<<"wrng selection";

cout<<"\ndo you want to continue:";

break;

}c=getch();

}getch();}