#include <stdio.h>

typedef struct _node {
   char element;
   struct _node *next;
} node;

typedef struct {
   node *front;
   node *back;
} queue;

queue init ()
{
   queue Q;

   /* Create the dummy node */
   Q.front = (node *)malloc(sizeof(node));
   Q.front -> element = ' ';
   Q.front -> next = NULL;
   Q.back = Q.front;
   return Q;
}

int isEmpty ( queue Q )
{
   return (Q.front == Q.back);
}

int isFull ( queue Q )
{
   return 0;
}

char front ( queue Q )
{
   if (isEmpty(Q)) {
      fprintf(stderr,"front: Queue is empty\n");
      return '\0';
   }
   return Q.front -> element;
}

queue enqueue ( queue Q , char ch )
{
   node *C;
   if (isFull(Q)) {
      fprintf(stderr,"enqueue: Queue is full\n");
      return Q;
   }

   /* Create new node */
   C = (node *)malloc(sizeof(node));
   C -> element = ch;
   C -> next = NULL;

   /* Adjust the back of queue */
   Q.back -> next = C;
   Q.back = C;

   return Q;
}

queue dequeue ( queue Q )
{
   if (isEmpty(Q)) {
      fprintf(stderr,"dequeue: Queue is empty\n");
      return Q;
   }

   /* Make the front of the queue the new dummy node */
   Q.front = Q.front -> next;
   Q.front -> element = '\0';

   return Q;
}

void print ( queue Q )
{
   node *G;

   G = Q.front -> next;
   while (G != NULL) {
      printf("%c", G -> element);
      G = G -> next;
   }
}

int main ()
{
   queue Q;

   Q = init(); printf("Current queue : "); print(Q); printf("\n");
   Q = enqueue(Q,'h'); printf("Current queue : "); print(Q); printf("\n");
   Q = enqueue(Q,'w'); printf("Current queue : "); print(Q); printf("\n");
   Q = enqueue(Q,'r'); printf("Current queue : "); print(Q); printf("\n");
   Q = dequeue(Q); printf("Current queue : "); print(Q); printf("\n");
   Q = dequeue(Q); printf("Current queue : "); print(Q); printf("\n");
   Q = enqueue(Q,'c'); printf("Current queue : "); print(Q); printf("\n");
   Q = dequeue(Q); printf("Current queue : "); print(Q); printf("\n");
   Q = dequeue(Q); printf("Current queue : "); print(Q); printf("\n");
   Q = dequeue(Q); printf("Current queue : "); print(Q); printf("\n");
}