队列的实现0

本节介绍队列的定义及基本操作。

1）队列定义：

typedef struct __queue queue;
typedef struct __node  node;

struct __queue
{
	struct __node *front;
	struct __node *rear;

	int size;
};

struct __node
{
	struct __node *pre;
	struct __node *next;
	void *data;
};

2）基本操作：

queue *create(void *data)
{
	queue *q = NULL;
	node  *p = NULL;	
	
	q = (queue *)malloc(sizeof(struct __queue));

	if (q == NULL)
	{
		perror("create queue node failed!\n");
		return NULL;
	}

	q->front = NULL;
	q->rear  = NULL;

	q->size = 0;

	return q;
}

int en_queue(queue *q, void *data)
{
	node *p;

	if (q == NULL)
	{
		perror("invalid queue!\n");
		return -1;
	}
	
	if (q->size > MAX_NODE)
	{
		perror("beyond max queue size!\n");
		return -1;
	}

	p = (node *)malloc(sizeof(struct __node));
	if (p == NULL)
	{
		perror("alloc new node failed!\n");
		return -1;
	}
		
	p->data = malloc(sizeof(int));
	*(int *)(p->data) = *(int *)data;

	if (q->rear == NULL && q->front == NULL)
	{
		//add first node here;
		q->front = p;
		q->front->pre = NULL;
		q->front->next = NULL;

		q->rear = p;
		q->rear->pre = NULL;
		q->rear->next = NULL;
	}
	else
	{
		q->rear->next = p;
		p->pre  = q->rear;
		p->next = NULL;	
		q->rear = p;
	}

	(q->size) ++;

	return 0;
}

int de_queue(queue *q, void *data)
{
	node *p = NULL;
	
	if (q == NULL || q->size <= 0)
	{
		perror("invalid queue!\n");
		return -1;
	}

	p = q->front;
	*(int *)data = *(int *)(p->data);
	
	if (p->next != NULL)
	{
		q->front = p->next;
		q->front->pre = NULL;
	}

	(q->size) --;

	free(p->data);
	free(p);

	return 0;
}

int destory_queue(queue *q)
{
	node *p = NULL;
	
	if (q == NULL)
		return 0;

	for (p = q->front; p != NULL; p = p->next)
	{
		free(p->data);
		free(p);
	}

	free(q);

	return 0;
}

3）打印所有元素：

int dump_queue(queue *q)
{
	node *p = NULL;
	int count = 0;
	
	if (q == NULL)
	{
		perror("invalid queue!\n");	
		return -1;
	}
	
	for(p = q->front; p != NULL; p = p->next, count ++)
	{
		if (count != 0 && count % LINE_NUM == 0)
			printf("\n");		

		printf("%d\t", *(int *)(p->data));
	}

	printf("\n");

	return 0;
}

下一节将介绍测试代码及说明。