cirqueue.c

#include<stdio.h>
#include<stdlib.h>
#define MAX 10

int cqueue_arr[MAX];
int front=-1;
int rear=-1;

void display();
void insert(int item);
int del();
int peek();
int isEmpty();
int isFull();

int main()
{
int choice,item;
while(1)
{
printf("\n1.Insert\n");
printf("2.Delete\n");
printf("3.Peek\n");
printf("4.Display\n");
printf("5.Quit\n");
printf("\nEnter your choice : ");
scanf("%d",&choice);

switch(choice)
{
case 1 :
printf("\nInput the element for insertion : ");
scanf("%d",&item);
insert(item);
break;
case 2 :
printf("\nElement deleted is : %d\n",del());
break;
case 3:
printf("\nElement at the front is  : %d\n",peek());
break;
case 4:
display();
break;
case 5:
exit(1);
default:
printf("\nWrong choice\n");
}
}
return 0;
}

void insert(int item)
{
if(isFull())
{
printf("\nQueue Overflow\n");
return;
}
if(front == -1)
front=0;
if(rear==MAX-1)
rear=0;
else
rear=rear+1;
cqueue_arr[rear]=item ;
}

int del()
{
int item;
if(isEmpty())
{
printf("\nQueue Underflow\n");
exit(1);
}
item=cqueue_arr[front];
if(front==rear)
{
front=-1;
rear=-1;
}
else if(front==MAX-1)
front=0;
else
front=front+1;
return item;
}

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

int isFull()
{
if((front==0 && rear==MAX-1) || (front==rear+1))
return 1;
else
return 0;
}

int peek()
{
if(isEmpty())
{
printf("\nQueue Underflow\n");
exit(1);
}
return cqueue_arr[front];
}

void display()
{
int i;
if(isEmpty())
{
printf("\nQueue is empty\n");
return;
}
printf("\nQueue elements :\n");
i=front;
if(front<=rear)
{
while(i<=rear)
printf("%d\t",cqueue_arr[i++]);
}
else
{
while(i<=MAX-1)
printf("%d\t",cqueue_arr[i++]);
i=0;
while(i<=rear)
printf("%d\t",cqueue_arr[i++]);
}
printf("\n");
}