Queue.cpp

#include<stdio.h>
#define qsize 5
struct queue
{
	int arr[qsize];
	int f,r;
};
typedef struct queue Queue;
void enqueue(Queue *q, int x)
{
	if(q->r==qsize-1)
		printf("QUEUE OVERFLOW\n");
	else
		q->arr[++q->r]=x;
}
int dequeue(Queue *q)
{
	if(q->f-q->r==1)
		printf("Queue Underflow");
	else 
		return(q->arr[q->f++]);
}
int main()
{
	Queue q;
	q.f=0;
	q.r=-1;
	while(1)
	{
		printf("Enter 1 to Enqueue\nEnter 2 to Dequeue\nEnter 3 to Display All Elements\nEnter 0 to Exit\n");
		int c;
		scanf("%d",&c);
		switch(c)
		{
			case 0: printf("Ended\n"); return 0;
			case 1: printf("Enter Element to Enqueue\n");
				int x;
				scanf("%d",&x);
				enqueue(&q,x);
				break;
			case 2: if(q.f-q.r==1)
					printf("Queue Undeflow\n");
				else
					printf("Dequeued Element is %d\n",dequeue(&q));
				break;
			case 3: printf("Elements of Queue Are\n");
				if(q.f-q.r==1)
				{
					printf("Queue is Empty\n");
					break;
				}
				int i;
				for(i=q.f;i<=q.r;i++)
					printf("%d ",q.arr[i]);
				printf("\n");
				break;
			default: printf("Wrong Choice\n");
		}
	}
	return 0;
}