A circular queue can be implemented through arrays or linked lists. Program 6 gives the array implementation of any circular queue.

Program 6: Array implementation of any Circular queue

include "stdio.h"

void add(int);

void deleteelement(void);

int max=10;         /*the maximum limit for queue has been set*/

static int queue[10];

int front=0, rear=-1; /*queue is initially empty*/

void main()

{

int choice,x;

printf ("Enter # for insertion & $ for removal of front the queue and * for exit");

printf("Enter your choice");

 scanf("%d",&choice);

switch (choice)

{

case 1 :

printf ("Enter element for insertion in queue:");

scanf("%d",&x);

add(x);

break;

case 2 :

deleteelement();

break;

}

}

void add(int y)

{

if(rear == max-1)

rear = 0;

else

rear = rear + 1;

if( front == rear && queue[front] != NULL)

printf("Queue Overflow");

else

queue[rear] = y;

}

void deleteelement()

{

int deleted_front = 0;

if (front == NULL)

printf("Error - Queue empty");

else

{

deleted_front = queue[front];

queue[front] = NULL;

if (front == max-1)

front = 0;

else

front = front + 1;

}

}