Data-Structure-Algorithm/QueueUsingArray.cpp at main · aruncode49/Data-Structure-Algorithm · GitHub

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#include<iostream>
#include<stdio.h>
usingnamespacestd;

#defineQUEUE_UNDERFLOW1; // defining an exception for empty queue;

classQueue
{
private:
int capacity;
int front;
int rear;
int *ptr;
public:
Queue();
Queue(int);
Queue(Queue&);
 Queue& operator=(Queue &);
voidinsertAtRear(int);
boolisOverflow();
boolisUnderflow();
intviewRearElement();
intviewFrontElement();
voiddeleteFront();
intcountElement();
~Queue();

};

Queue::Queue()
{
 capacity = 0;
 front = rear = -1;
 ptr = NULL;
}

Queue::Queue(int cap) // constructor
{
 capacity = cap;
 front = rear = -1; // initially queue is empty.
 ptr = newint[cap];
}

Queue::Queue(Queue& q) // copy constructor
{
 capacity = q.capacity;
 front = q.front;
 rear = q.rear;
 ptr = newint[capacity];
for(int i = 0; i<capacity; i++)
 ptr[i] = q.ptr[i];
}

Queue& Queue::operator=(Queue &q)
{
if(ptr != NULL)
delete [] ptr; // this-> deleting the memory of pointer for( if it containes any other location)
 capacity = q.capacity;
 front = q.front;
 rear = q.rear;
 ptr = newint[capacity];
for(int i = 0; i<capacity; i++)
 ptr[i] = q.ptr[i];
return *this;
}

voidQueue::insertAtRear(int data)
{
if(isOverflow()) // when queue is full
 cout<<"Queue Overflow! Data cannot inserted.";

elseif(isUnderflow()) // when queue is empty
 {
 front = rear = 0;
 ptr[front] = data;
 }
elseif(rear == capacity-1) // when queue is full from rear but front space is empty
 {
 rear = 0;
 ptr[rear] = data;
 }
else// normal case
 {
 rear++;
 ptr[rear] = data;
 }
}

boolQueue::isOverflow() // for checking our queue is full or not
{
if(rear == capacity-1 && front == 0 || rear + 1 == front)
returntrue;
else
returnfalse;
}

boolQueue::isUnderflow() // for checking our queue is empty or not
{
if(rear == -1 && front == -1) // checking for both rear or front is not necessary
returntrue;
else
returnfalse;
}

intQueue::viewRearElement() // for getting last or latest element inserted in queue
{
if(isUnderflow())
throwQUEUE_UNDERFLOW;
return ptr[rear];
}

intQueue::viewFrontElement() // for getting first or oldest element inserted in queue
{
if(isUnderflow())
throwQUEUE_UNDERFLOW;
return ptr[front];
}

voidQueue::deleteFront()
{
if(isUnderflow()) // when queue is empty
 cout<<"Queue Underflow! Deletion not possible.";
elseif(front == rear) // when queue has only one element
 front = rear = -1;
elseif(front == capacity-1) // when front is our last element
 front = 0;
else// normal case
 front++;
}

intQueue::countElement()
{
if(isOverflow()) // if queue is full
return capacity;
elseif(isUnderflow()) // if queue is empty
return0;
elseif(rear == front) // if queue has only one element
return1;
elseif(rear > front) // if rear is greater than front
return (rear-front+1);
else
return capacity-front+rear+1; // if any case other than all these

}

Queue::~Queue()
{
if(ptr != NULL)
delete [] ptr; // not necessary to check the NULL Condition because of parametrised constructor.
}