#include <stdio.h> #include <stdlib.h> struct node { int info; struct node *ptr; }*front,*rear,*temp,*front1; int frontelement(); void enq(int data); void deq(); void empty(); void display(); void create(); void queuesize(); int count = 0; void main() { int no, ch, e; printf("\t\t\t\t\tChose one from the below options...\n"); printf("\n\t\t\t\t\t 1 - Enque"); printf("\n\t\t\t\t\t 2 - Deque"); printf("\n\t\t\t\t\t 3 - Display"); printf("\n\t\t\t\t\t 4 - Exit"); create(); while (1) { printf("\n Enter choice : "); scanf("%d", &ch); switch (ch) { case 1: printf("Enter data : "); scanf("%d", &no); enq(no); break; case 2: deq(); break; case 3: display(); break; case 4: exit(0); default: printf("Wrong choice, Please enter correct choice "); break; } } } void create() { front = rear = NULL; } void queuesize() { printf("\n Queue size : %d", count); } void enq(int data) { if (rear == NULL) { rear = (struct node )malloc(1sizeof(struct node)); rear->ptr = NULL; rear->info = data; front = rear; } else { temp=(struct node )malloc(1sizeof(struct node)); rear->ptr = temp; temp->info = data; temp->ptr = NULL; rear = temp; } count++; } void display() { front1 = front; if ((front1 == NULL) && (rear == NULL)) { printf("Queue is empty."); return; } while (front1 != rear) { printf("%d ", front1->info); front1 = front1->ptr; } if (front1 == rear) printf("%d", front1->info); } void deq() { front1 = front; if (front1 == NULL) { printf("\n Error: Trying to display elements from empty queue"); return; } else if (front1->ptr != NULL) { front1 = front1->ptr; printf("\n Dequed value : %d", front->info); free(front); front = front1; } else { printf("\n Dequed value : %d", front->info); free(front); front = NULL; rear = NULL; } count--; }