C++ Modify the Queue class to include appropriate error messages if invalid conditions occurfor example, trying to dequeue an item when the queue is empty.

A SIMPLE QUEUE CLASS

main.cpp

/*******************************

* Week 2 lesson: *

* a simple Queue class *

*******************************/

#include "Queue.h"

#include

using namespace std;

int main()

{

Queue q;

cout << "Insertion of 10 characters in q" << endl;

for(int i=0; i < q.getSize(); i++)

{

char x = 32 + rand()%95;

cout << x << endl;

q.enqueue(x);

}

cout << endl

<< "Displaying and deleting elements from q" << endl;

while(!q.isEmpty())

{

cout << "Item at the front: " << q.getFront() << endl;

q.dequeue();

}

return 0;

}

Queue.cpp

/*******************************

* Week 2 lesson: *

* a simple Queue class *

*******************************/

#include "Queue.h"

/*

* Constructor. Initializes the queue.

*/

Queue::Queue()

{

front = 0;

back = SIZE-1;

count = 0;

}

/*

* Determines whether the queue is empty.

*

* Returns true if the queue is empty, false otherwise.

*/

bool Queue::isEmpty()

{

return count == 0;

}

/*

* Adds an element to the back of the queue.

*

* x: element to be added to the queue.

*/

void Queue::enqueue(char x)

{

back = (back+1)%SIZE;

list[back] = x;

count++;

}

/*

* Removes the element in the front of the queue.

*/

void Queue::dequeue()

{

front = (front+1)%SIZE;

count--;

}

/*

* Returns the element in the front of the queue. Does not remove it.

*/

char Queue::getFront()

{

return list[front];

}

/*

* Returns the size of the queue.

*/

int Queue::getSize()

{

return SIZE;

}

Queue.h

/*******************************

* Week 2 lesson: *

* a simple Queue class *

*******************************/

/*

* Class implementing a Queue ADT.

*/

class Queue

{

public:

Queue();

bool isEmpty();

void enqueue(char);

void dequeue();

char getFront();

int getSize();

private:

static const int SIZE = 10; //size of the queue array

char list[SIZE]; //array to store the queue items

int count; //number of items in the queue

int front, back; //front and back locations

};