circular_queue.c

#include<stdio.h>
int a[10];
void main()
{
	int n,i,item,ch;
	printf("Enter the number of elements:");
	scanf("%d",&n);
	int front=-1,rear=-1;
	do
	{
		printf("\n1. ADD  2.DELETE  3.DISPLAY  4.EXIT");
		printf("Enter the choice :");
		scanf("%d",&ch);
		switch(ch)
		{
			case 1: printf("Enter the element:");
					scanf("%d",&item);
					if( (front == rear + 1) || (front == 0 && rear == n-1))
						printf("The Queue is full");
					else
					{
						if(front == -1) front = 0;
        				rear = (rear + 1)%n;
        				a[rear] = item;
						printf("\n Inserted -> %d", item);
					}
					break;
			case 2:
					if(front == -1)
					printf("\nCircular Queue is Empty! Deletion is not possible!!!\n");
					else{
		      			item = a[front];
	        			if (front == rear){
            				front = -1;
            				rear = -1;
        				}
        				else {
            				front = (front + 1)%n;
			        	}
						printf("\n Deleted element -> %d \n", item);
			        }
					break;
			case 3:	if(front == -1)
					printf(" \n Empty Queue\n");
					else
			        {
						printf("Enter the element in Queue are:\n");
				        for( i = front; i!=rear; i=(i+1)%n)
						{
							printf("%d ",a[i]);
				        }
						printf("%d ",a[i]);
			        }
					break;
			case 4: printf("Exiting from Queue\n");
					break;
			default:   printf("\nInvalid choice");
						break;
		}
	}while(ch!=4);
}