数据结构--链式栈

一.链式栈的栈顶在哪里?

二.链栈的结构:

typedef struct LSNode{
int data;
struct LSNode* next;
}LSNode ,*PLStack;

//链栈的节点.由于栈顶在第一个数据节点,所以不需要top指针

三.链式栈的实现:

//初始化

	LSNode* p = (LSNode*)malloc(sizeof(LSNode));
	assert(p != NULL);

	p->data = val;
	p->next = ps->next;
	ps->next = p;

	return true;
}
//获取栈顶元素的值,但是不删除
bool  GetTop(PLStack ps, int* rtval )
{
	assert(ps != NULL);
	if (ps == NULL)
		return false;

	if (IsEmpty(ps))
		return   false;

		*rtval=ps->next->data;
		return true;
}
//获取栈顶元素的值,但是删除
bool   Pop(PLStack ps, int* rtval)
{
	assert(ps != NULL);
	if (ps == NULL)
		return false;

	if (IsEmpty(ps))
		return   false;

	LSNode* p = ps->next;
	*rtval = p->data;

	ps->next = p->next;
	free(p);
	return true;
}
//判空
bool IsEmpty(PLStack ps)
{
	return ps->next == NULL;
}
//获取栈中有效元素的个数
int  GetLength(PLStack ps)
{
	assert(ps != NULL);
	if (ps == NULL)
		return -1;
	int count = 0;
	for (LSNode* p = ps->next; p != NULL; p = p->next)
	{
		count++;
	}
	return count;
}
//清空所有的数据
void Clear(PLStack ps)
{
	Destroy(ps);
}
//销毁
void Destroy(PLStack ps)
{
	//总是删除第一个数据节点
	LSNode* p;
	while (ps->next != NULL)
	{
		p = ps->next;
		ps->next = p->next;
		free(p);
	}
}