C言語でキュー

queue.c

#include <stdio.h>

#define QUEUESIZE 3000

struct Queue {
  int buffer[QUEUESIZE];
  int length;
};

int enqueue(struct Queue *queue, int data) {

  queue->buffer[queue->length] = data;
  queue->length++;

  return 0;
};

int dequeue(struct Queue *queue) {

  int res;
  int i;

  if (queue->length > 0) {
    res = queue->buffer[0];

    // 配列を先頭へずらす
    for (i = 0; i < queue->length - 1; i++) {
      queue->buffer[i] = queue->buffer[i+1];
    };

    queue->length--;
  } else {
    res = 0;
  }

  return res;

};

int main(int argc, char const* argv[])
{
  struct Queue alice;
  alice.length = 0;

  enqueue(&alice, 1);
  enqueue(&alice, 2);
  enqueue(&alice, 3);

  printf("%d\n",dequeue(&alice));
  printf("%d\n",dequeue(&alice));
  printf("%d\n",dequeue(&alice));
  
  return 0;
};