queue0.h

#include <stdlib.h>

typedef struct {
   int head, tail;
   int QA[MaxQ];
} QType, *Queue;

Queue initQueue() {
   Queue qp = (Queue) malloc(sizeof(QType));
   qp -> head = qp -> tail = 0;
   return qp;
}

int empty(Queue Q) {
   return (Q -> head == Q -> tail);
}

void enqueue(Queue Q, int n) {
   if (Q -> tail == MaxQ - 1) Q -> tail = 0;
   else ++(Q -> tail);
   if (Q -> tail == Q -> head) {
      printf("\nQueue is full\n");
      exit(1);
   }
   Q -> QA[Q -> tail] = n;
}

int dequeue(Queue Q) {
   if (empty(Q)) {
      printf("\nAttempt to remove from an empty queue\n");
      exit(1);
   }
   if (Q -> head == MaxQ - 1) Q -> head = 0;
   else ++(Q -> head);
   return Q -> QA[Q -> head];
}