Data Structure- 5 Queue Concept using Circular Array

// In this article we will Learn concept of circular array to

implement the queue concept because as we can see the in linear array there is a no way to store new item even if there is a space after deleting an element ! 

with circular array w will use MAX-1 index of array and initially we will put front and rear to index zero position !

1. when we need to insert a data we just increment the rear and insert the data !
2. When we need to delete the data we just increase the front and print the data!

Only important point is that when during insertion if rear== front then it means the queue is full now and we will put rear one position back , if rear =0 then one position back is MAX-1; and if rear != 0 then one position back is rear-1;

In order to move rear and front we will use mod operator!

/******************************************************************************
Queue Concept using Circular Array !               
@Mukesh Mann dated 16-02-2020
*******************************************************************************/

#define MAX 4

enqueue(int);

//void delete();

void display();

int queue_array[MAX];

int rear = 0;

int front = 0;

 enqueue(int item)

{

    //int item;

     rear=(rear+1)%MAX;

    if (front==rear)

    {

        printf("Queue Overflow \n");

        if(rear==0)

        {

          rear=MAX-1; 

        }

        else {

        rear=rear-1;}

        return;

    }

    else

    {

    queue_array[rear]= item;

    printf("iTEM INSERTED is %d\n",queue_array[rear]);

       return;

    }

} /* End of Enqueue() */

 deqeue()

{

    if(front==rear)

    {

         printf("Queue is empty on");

         return -1;

    }

    else

    {

          front=(front+1)%MAX;

         int item= queue_array[front];

         printf("Deleted Item is %d\n",item);

          return item;

    }

  

} /* End of deqeue() */

 main()

 {

    

// Here we try to insert 3 item using a loop

 // initially front and rear are point to zero and we will utilize only max-1 index of circular array

     for (int i = front; i <= MAX-1; i++){

     enqueue(i);

      }

     

      for (int i = front; i <= MAX-1; i++){

       deqeue();

      }

    

}