DS-Record-mca-03) write a program to implement operations on circular queues.

 Program:-03

AIM:-

write a program to implement operations on circular queues. 

code:-

#include <stdio.h>
#include <conio.h>
#define SIZE 3
int items[SIZE];
int front = -1, rear = -1;
// Check if the queue is full
int isFull() 
{
  if ((front == rear + 1) || (front == 0 && rear == SIZE - 1))
  return 1;
  return 0;
}
// Check if the queue is empty
int isEmpty() 
{
  if (front == -1)
  return 1;
  return 0;
}
// Adding an element
void enQueue(int element)
{
  if (isFull())
  {
    printf("\n Queue is full!! \n");
  }
  else 
  {
    if (front == -1) front = 0;
    rear = (rear + 1) % SIZE;
    items[rear] = element;
    printf("Inserted -> %d\t", element);
  }
}
// Removing an element
int deQueue() 
{
  int element;
  if (isEmpty()) 
  {
    printf("\n Queue is empty !! \n");
    return (-1);
  } else 
  {
    element = items[front];
    if (front == rear) 
    {
      front = -1;
      rear = -1;
    }
    // Q has only one element, so we reset the
    // queue after dequeing it. ?
    else 
    {
      front = (front + 1) % SIZE;
    }
    printf("\n Deleted element -> %d \n", element);
    return (element);
  }
}
// Display the queue
void display() 
{
  int i;
  if (isEmpty())
  {
    printf(" \n Empty Queue\n");
  }else
  {
    printf("\n Front -> %d ", front);
    printf("\n Items -> ");
    for (i = front; i != rear; i = (i + 1) % SIZE) 
    {
      printf("%d ", items[i]);
    }
    printf("%d ", items[i]);
    printf("\n Rear -> %d \n", rear);
  }
}
//Main function
void main()
{
  clrscr();
  // Fails because front = -1
  deQueue();
  enQueue(1);
  enQueue(2);
  enQueue(3);
  enQueue(4);
  enQueue(5);
  // Fails to enqueue because front == 0 && rear == SIZE - 1
  enQueue(6);
  display();
  deQueue();
  display();
  enQueue(7);
  display();
  // Fails to enqueue because front == rear + 1
  enQueue(8);
  getch();
}

Output:-