queue.c

#include <stdio.h>

#define CAPACITY 10

typedef enum
{
  false,
  true
}
bool;

typedef struct
{
  int head;
  int length;
  int elements[CAPACITY];
}
queue;

bool dequeue(queue* q, int* element);

int
main (int argc, char *argv[])
{
  int b; // dequeued element
  queue q;
  q.head = 0;
  q.length = 4;
  q.elements[0] = 6;
  q.elements[1] = 2;
  q.elements[2] = 3;
  q.elements[3] = 1;

  dequeue(&q, &b);
  dequeue(&q, &b);

  if ( b == true) printf("dequeue() success\n");

  for (int i = q.head; i <= q.length + 1; i++)
    {
      printf("%d ", q.elements[i]);
    }
  return 0;
}

bool dequeue(queue* q, int* element)
{
  if (q->length > 0)
    {
      *element = q->elements[q->head];
      q->head = (q->head + 1) % CAPACITY;
      q->length--;
      printf("dequeue(): %d\n", *element);
      printf("head is: %d\n", q->head);

      return true;
    }
  return 0;
}