circularqueuearray.h

#define MAXQUEUE 4
#define TRUE 1
#define FALSE 0

typedef struct queue
{
	int a[MAXQUEUE];
	int front;
	int rear;
}Q;


// function prototypes
void initQueue(Q *); // initializing the queue
void append(Q *, int, int *); // enqueue an integer to the queue
void serve(Q *, int *, int *);  // dequeue an element out of the queue

// function definitions
// initializing the queue
void initQueue(Q *pQueue)
{
	pQueue->front = pQueue->rear = MAXQUEUE-1;
}

// enqueue an integer to the queue
void append(Q *pQueue,int toAppend,int *overflow)
{
	int newRear;
	newRear = (pQueue->rear == MAXQUEUE-1) ? 0 : (pQueue->rear)+1;
	if(newRear == pQueue->front)
		*overflow = TRUE;
	else
	{
		*overflow = FALSE;
		pQueue->rear = newRear;
		pQueue->a[pQueue->rear] = toAppend;
	}
}

// dequeue an element out of the queue
void serve(Q *pQueue,int *served,int *underflow)
{
	if(pQueue->front==pQueue->rear)	
		*underflow = TRUE;
	else
	{
		*underflow = FALSE;
		pQueue->front = (pQueue->front == MAXQUEUE-1) ? 0 : (pQueue->front)+1;
		*served = pQueue->a[pQueue->front];
	}
}