5.2 Queue using Array

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>

int queue[5];
int front=-1;
int rear=-1;

void insert()
{
	int item;
	printf("Enter Data : ");
	scanf("%d",&item);
	if(front==-1 && rear==-1)
	{
		front++;
		rear++;
		queue[rear]=item;
	}
	else if(rear==4)
	{
		printf("OverFlow");
	}
	else
	{
		rear++;
		queue[rear]=item;
	}
}

void delete()
{
	if(front==-1 && rear==-1)printf("UnderFlow");
	else if(front==rear)
	{
		front=-1;
		rear=-1;
	}
	else
	{
		rear--;
	}
}
void display()
{
	if(front==-1 && rear==-1)
	{
		printf("UnderFlow");
	}
	else if(front==rear)
	{
		printf("%d",queue[rear]);
	}
	else
	{
		int temp=front;
		while(temp!=rear)
		{
			printf("%d ",queue[temp]);
			temp++;
		}
		printf("%d",queue[temp]);
	}
}

int isEmpty()
{
	if(front==-1 && rear==-1) return 1;
	else return 0;
}

int isFull()
{
	if(rear==4)return 1;
	else return 0;
}

void main()
{
	while(1)
	{
		int ch;
		clrscr();
		printf("\n1. Insert");
		printf("\n2. Delete");
		printf("\n3. Display");
		printf("\n4. UnderFlow");
		printf("\n5. OverFlow");
		printf("\n6. EXIT");
		printf("\nEnter Your Choice : ");
		scanf("%d",&ch);
		switch(ch)
		{
			case 1:
				insert();
				break;
			case 2 :
				delete();
				break;
			case 3 :
				display();
				break;
			case 4 :
				if(isEmpty()) printf("\nUnderFlow");
				else printf("\nNo UnderFlow");
				break;
			case 5 :
				if(isFull())printf("\nOverflow");
				else printf("\nNo OverFlow");
				break;
			case 6 :
				exit(0);
				break;
			default:
				printf("\nInvalid Choice");

		}
		getch();
	}
}