队列的实现(链表)-C语言

队列的实现(链表)

队列：只允许在一端进行插入数据操作，在另一端进行删除数据操作的特殊线性表，队列具有先进先出FIFO(First In First Out)。

入队列： 进行插入操作的一端称为队尾。
出队列： 进行删除操作的一端称为队头。

队列也可以数组和链表的结构实现，使用链表的结构实现更优一些，因为如果使用数组的结构，出队列在数组头上出数据，效率会比较低。

#include 
#include 
#include 
typedef int QDataType;
typedef struct QueueNode
{
	QDataType data;
	struct QueueNode *next;
}QueueList;

void QueueInit(QueueList **head);
void QueueDestory(QueueList *head);
QueueList *QueuePush(QueueList *head, QDataType data);
bool QueueEmpty(QueueList *head);
void QueuePop(QueueList **head);
QDataType QueueBack(QueueList *head);
QDataType QueueFront(QueueList *head);
size_t QueueSize(QueueList *head);
void QueuePrint(QueueList *head);

int main()
{
	QueueList *head;
	QueueInit(&head);
	QueuePrint(head);
	for(int i = 0; i < 4; i++)
	{
		head = QueuePush(head, i);
	}
	QueuePrint(head);
	head = QueuePush(head, 89);
	printf("89入栈：n");
	QueuePrint(head);
	printf("出栈：n");
	QueuePop(&head);
	QueuePrint(head);
	printf("栈头数据：%dn", QueueFront(head));
	printf("栈尾数据：%dn", QueueBack(head));
	printf("栈大小：%dn", QueueSize(head));
	return 0;
}

//队列初始化
void QueueInit(QueueList **head)
{
//	*head = (QueueList *)malloc(sizeof(QueueList));
	*head = NULL;
}

//队列的销毁
void QueueDestory(QueueList *head)
{
	if(head == NULL)
	{
		return ;
	}
	QueueList *tmp = head;
	while(tmp)
	{
		QueueList *mmp = tmp->next;
		free(tmp);
		tmp = mmp;
	}
}

//进队列
QueueList *QueuePush(QueueList *head, QDataType data)
{
//	assert(head);
	QueueList *newnode = (QueueList *)malloc(sizeof(QueueList));
	if(newnode == NULL)
	{
		printf("开辟空间失败！");
		exit(-1);
	}
	newnode->data = data;
	newnode->next = NULL;
	if(head == NULL)
	{
		head = newnode;
	}
	else
	{
		QueueList *tmp = head;
		while(tmp->next != NULL)
		{
			tmp = tmp->next;
		}
		tmp->next =newnode;
	}
	return head;
}

//出队列
void QueuePop(QueueList **head)
{
	assert(*head);
    assert(!QueueEmpty(*head));  //head是否为空
    QueueList *tmp = *head;
    (*head) = (*head)->next;
    free(tmp);
}

//队列是否为空
bool QueueEmpty(QueueList *head)
{
	assert(head);
	return head == NULL;
}

//获取头数据
QDataType QueueFront(QueueList *head)
{
	assert(head);
    assert(!QueueEmpty(head));  //head是否为空
    return head->data;
}

//获取尾数据
QDataType QueueBack(QueueList *head)
{
	assert(head);
    assert(!QueueEmpty(head));  //head是否为空
    QueueList *tmp = head;
	while(tmp->next != NULL)
	{
		tmp = tmp->next;
	}
    return tmp->data;
}

//获取队列的长度
size_t QueueSize(QueueList *head)
{
	assert(head);
    assert(!QueueEmpty(head));  //head是否为空
    QueueList *tmp = head;
    size_t cnt = 0;
	while(tmp != NULL)
	{
		cnt++;
		tmp = tmp->next;
	}
	return cnt;
}

//队列的打印
void QueuePrint(QueueList *head)
{
	for(QueueList *p = head; p != NULL; p = p->next)
	{
		printf("%d  %#X  n", p->data, p);
	}
}