Program to Implement Double Ended Queue

Here is the code of program:- 

#include<stdio.h>
#include<conio.h>
void main()
{
	int front=0,rear=-1,queue[20],n,data,i=0,ch;
	clrscr();
	printf("Enter size of Queue: ");
	scanf("%d",&n);
	printf("1. Insert from Rear.\n");
	printf("2. Insert from Front.\n");
	printf("3. Delete from Rear.\n");
	printf("4. Delete from Front.\n");
	printf("5. Display from Rear.\n");
	printf("6. Display from Front.\n");
	printf("7. Exit.\n");
	do
		{
		printf("\nEnter your choice: ");
		scanf("%d",&ch);
		switch(ch)
			{
			case 1:
				if((rear>=(n-1))&&(front==0))
				{
					printf("Overflow\n");
				}
				else if((rear>=(n-1))&&(front>0))
				{
					printf("Insertion from Front is possible only.\n");
				}
				else
				{
					printf("Enter data: ");
					scanf("%d",&data);
					rear=rear+1;
					queue[rear]=data;
				}
				break;
			case 2:
				if((rear>front)&&(front>0))
				{
				       printf("Enter data: ");
				       scanf("%d",&data);
				       front=front-1;
				       queue[front]=data;
				}
				else if((rear>=(n-1))&&(front==0))
				{
					printf("Overflow\n");
				}
				else
				{
					printf("Enter data: ");
					scanf("%d",&data);
					for(i=rear+1;i>front;i--)
					{
						queue[i]=queue[i-1];
					}
					queue[front]=data;
					rear=rear+1;
				}
				break;
			case 3:
				if((front==0)&&(rear==-1))
				{
					printf("Underflow\n");
				}
				else
				{
					data=queue[rear];
					if(rear>front-1)
					{
						printf("Deleted item %d\n",data);
					}
					else
					{
						printf("Underflow\n");
					}
					rear=rear-1;
				}
				break;
			case 4:
				if((front==0)&&(rear==-1))
				{
					printf("Underflow\n");
				}
				else
				{
					data=queue[front];
					if(front<rear+1)
					{
						printf("Deleted item %d\n",data);
					}
					else
					{
						printf("Underflow\n");
					}
					front=front+1;
				}
				break;
			case 5:
				for(i=rear;i>front;i--)
				{
					printf("%d ",queue[i]);
				}
				if(i==front)
				{
					printf("%d\n",queue[i]);
				}
				else
				{
					printf("Queue is Empty\n");
				}
				break;
			case 6:
				for(i=front;i<rear;i++)
				{
					printf("%d ",queue[i]);
				}
				if(i==rear)
				{
					printf("%d\n",queue[i]);
				}
				else
				{
					printf("Queue is Empty\n");
				}
				break;
			case 7:
				exit(0);
			default:
				printf("Invalid option");

			}
		}while(ch>0&&ch<7);
	getch();
}