program of queues

/*Program of queue using array*/
# include
# define MAX 5

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

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

switch(choice)
{
case 1 :
insert();
break;
case 2 :
del();
break;
case 3:
display();
break;
case 4:
exit(1);
default:
printf("Wrong choice\n");
}/*End of switch*/
}/*End of while*/
}/*End of main()*/

insert()
{
int added_item;
if (rear==MAX-1)
printf("Queue Overflow\n");
else
{
if (front==-1) /*If queue is initially empty */
front=0;
printf("Input the element for adding in queue : ");
scanf("%d", &added_item);
rear=rear+1;
queue_arr[rear] = added_item ;
}
}/*End of insert()*/

del()
{
if (front == -1 || front > rear)
{
printf("Queue Underflow\n");
return ;
}
else
{
printf("Element deleted from queue is : %d\n", queue_arr[front]);
front=front+1;
}
}/*End of del() */

display()
{
int i;
if (front == -1)
printf("Queue is empty\n");
else
{
printf("Queue is :\n");
for(i=front;i<= rear;i++)
printf("%d ",queue_arr[i]);
printf("\n");
}
}/*End of display() */