#include <stdio.h>
#include <stdlib.h>
#define FULL 100
typedef struct node
{
int passenger;
struct node *next;
} node;
typedef struct queue
{
int count;
node *front;
node *rear;
} queue;
void initialize (queue *q)
{
q->count = 0;
q->front = NULL;
q->rear = NULL;
}
int isempty (queue *q)
{
return (q->rear == NULL);
}
void enqueue (queue *q, int value)
{
if (q->count < FULL)
{
node *tmp;
tmp = (node *) calloc(1, sizeof(node));
tmp->passenger = value;
tmp->next = NULL;
if (!isempty (q))
{
q->rear->next = tmp;
q->rear = tmp;
}
else
{
q->front = q->rear = tmp;
}
q->count++;
}
else
{
printf ("Sorry. The queue is full.\n");
}
}
int dequeue (queue *q)
{
node *tmp;
int n = q->front->passenger;
tmp = q->front;
q->front = q->front->next;
q->count--;
free (tmp);
return (n);
}
void display (node *head)
{
if (head == NULL)
{
printf ("NULL\n");
}
else
{
printf ("
", head -> passenger);
display(head->next);
}
}
int main (void)
{
queue *q;
q = (queue *) calloc(1, sizeof(queue));
initialize(q);
enqueue(q,1345);
enqueue(q,2678);
enqueue(q,3951);
printf ("Passengers waiting in line: ");
display(q->front);
dequeue(q);
printf("Passengers now waiting in line: ");
display(q->front);
return (0);
}
