Question

Objective:

In this assignment you will do the following: (1) manipulate pointers, (2) allocate memory dynamically,

(3) implement a default constructor, copy constructor and destructor, (4) use only one pointer to add to

the back and to dequeue from the front of the queue.

Assignment Description:

You will implement a doubly-linked circular queue of integers. Consider the following class declarations

when implementing BQUEUE. As always, you must comment your declaration and implementation files,

"BQUEUE.h" and "BQUEUE.cpp", respectively.

class bqnode

{

public:

int time;

bqnode *prev,

*next;

};

class BQUEUE

{

public:

BQUEUE( );

~BQUEUE( );

BQUEUE(const BQUEUE &);

void Enqueue(int);

void Dequeue( );

void Print( );

private:

bqnode *front; //use ONLY one pointer

};

Use the following driver called "BQUEUE_driver.cpp" to test your code:

#inlcude <iostream>

#include "BQUEUE.h"

using namespace std;

int main( )

{

  BQUEUE k;

k.Enqueue(60);

k.Print();

k.Enqueue(20);

k.Enqueue(30);

k.Print();

k.Enqueue(10);

k.Print();

k.Enqueue(50);

k.Enqueue(40);

k.Print();

BQUEUE j = k;

  j.Dequeue();

j.Print();

j.Dequeue();

j.Dequeue();

j.Dequeue();

j.Print();

j.Dequeue();

j.Dequeue();

j.Print();

j.Dequeue();

j.Dequeue();

return 0;

}

  

  

Answer 1

1. BQUEUE.h

#pragma once
#include <iostream>
class bqnode

{

public:

   int time;

   bqnode *prev,

       *next;

};

class BQUEUE
{
public:
   BQUEUE();
   ~BQUEUE();
   BQUEUE(const BQUEUE &);

   void Enqueue(int);

   void Dequeue();

   void Print();

private:

   bqnode * front; //use ONLY one pointer

};

2. BQUEUE.cpp

#include "BQUEUE.h"

using namespace std;

BQUEUE::BQUEUE()
{
}

BQUEUE::~BQUEUE()
{
}

BQUEUE::BQUEUE(const BQUEUE & otherList)
{
   if (otherList.front == NULL) return;

   front = new bqnode();
   bqnode *curr = front;
   bqnode *oldnode = otherList.front;
   curr->time = oldnode->time;
   curr->next = NULL;
   while (oldnode->next != NULL)
   {
       bqnode *newnode = new bqnode();
       newnode->time = oldnode->next->time;
       curr->next = newnode;
       newnode->prev = curr;
       curr = newnode;
       oldnode = oldnode->next;
   }
}

void BQUEUE::Enqueue(int newdata)
{
   bqnode* newnode = new bqnode();
   newnode->time = newdata;
   newnode->prev = NULL;
   newnode->next = front;
   if (front != NULL)
       front->prev = newnode;
   front = newnode;
}

void BQUEUE::Dequeue()
{
   // If queue is empty, return NULL.
   if (front == NULL)
       return;

   bqnode* ptr;
   ptr = front;
   while (ptr->next != NULL) {
       ptr = ptr->next;
   }

   bqnode * prev = ptr->prev;
   if (prev != NULL)
       prev->next = NULL;
   ptr = NULL;

}

void BQUEUE::Print()
{
   bqnode* ptr;
   ptr = front;
   cout << "Print array => " ;
   while (ptr != NULL) {
       cout << ptr->time << " ";
       ptr = ptr->next;
   }
   cout << endl;
}

3. Driver class

#include <iostream>

#include "BQUEUE.h"

using namespace std;

int main()

{

   BQUEUE k;

   k.Enqueue(60);

   k.Print();

   k.Enqueue(20);

   k.Enqueue(30);

   k.Print();

   k.Enqueue(10);

   k.Print();

   k.Enqueue(50);

   k.Enqueue(40);

   k.Print();

   BQUEUE j = k;

   j.Dequeue();

   j.Print();

   j.Dequeue();

   j.Dequeue();

   j.Dequeue();

   j.Print();

   j.Dequeue();

   j.Dequeue();

   j.Print();

   j.Dequeue();

   j.Dequeue();

   cout << "Press any key to exit";
   getchar();
   return 0;

}