DOUBLY QUEUE IMPLEMENTATION C++

// DOUBLY QUEUE IMPLEMENTATION
#include<iostream>

using namespace std;

struct Node{ //NODE STRUCTURE

Node *prev;

int data;

Node *next;

};

class Doubly_Queue{ //DOUBLY_QUEUE CLASS

Node *front;

Node *rear;

public:

Doubly_Queue()

{

front = NULL;

rear = NULL;

}

void insertion(int x) //INSERTION FUNCTION

{

Node *ptr = new Node;

ptr->data = x;

if(rear == NULL)

{

ptr->prev = NULL;

ptr->next = NULL;

rear = ptr;

front = ptr;

}

else

{

rear->next = ptr;

ptr->prev = rear;

ptr->next = NULL;

rear = ptr;

}

}

int remove() // REMOVE OR DELETE FUNCTION

{

int copy = front->data;

Node *rptr = front;

front = front->next;

if(front == NULL)

{

rear = NULL;

}

delete rptr;

return copy;

}

void previous() // PERVIOUS VALUES DISPLAYING FUNCTION

{

Node *curr = rear;

while(curr != NULL)

{

cout<<curr->data<<" ";

curr = curr->prev;

}

}

void display() // NORMAL DISPLAY FUNCTOIN

{

Node *curr = front;

while(curr != NULL)

{

cout<<curr->data<<" ";

curr = curr->next;

}

}

};

// MAIN DRIVEN...

int main()

{

Doubly_Queue q; // OBJECT OF CLASS

char choice;

do{

int input;

cout<<"1) TO INSERT: \n";

cout<<"2) TO REMOVE: \n";

cout<<"3) FOR PREVIOUS DISPLAY: \n";

cout<<"4) FOR NORMAL DISPLAYING: ";

cin>>input;

system("clear");

switch (input)

{

case 1:

int num;

cout<<"ENTER NUMBER TO INSERT :";

cin>>num;

q.insertion(num);

break;

case 2:{

cout<<"REMOVED NUMBER IS: "<<q.remove()<<endl;

break;

}

case 3:{

q.previous();

break;

}

case 4:{

q.display();

break;

}

default:

cout<<"ERROR 404: ";

break;

}

cout<<"DO YOU WANT TO MORE: (Y/N)...";

cin>>choice;

system("clear");

}while(choice == 'y');

return 0;

}

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