链式栈的实现

#include <stdio.h>
#include <stdlib.h>

typedef int ElemType;

typedef struct Node{
	ElemType data;
	struct Node *next;
}StackNode, Stack;

void Init(Stack *s);
bool IsEmpty(Stack *s);
void Push(Stack *s, ElemType e);
void Pop(Stack *s, ElemType *e);
void GetTop(Stack *s, ElemType *e);
void Print(Stack *s);
void Clear(Stack *s);

void Init(Stack *s)
{
	s->next = NULL;
}

bool IsEmpty(Stack *s)
{
	return (s->next == NULL) ? true : false;
}

void Push(Stack *s, ElemType e)
{
	StackNode *node = (StackNode *)malloc(sizeof(StackNode));
	node->data = e;
	node->next = s->next;
	s->next = node;
}

void Pop(Stack *s, ElemType *e)
{
	if (!IsEmpty(s))
	{
		StackNode *temp = s->next;
		*e = temp->data;
		s->next = temp->next;	
	}
}

void GetTop(Stack *s, ElemType *e)
{
	if (!IsEmpty(s))
		*e = s->next->data;
}

void Print(Stack *s)
{
	StackNode *p = s->next;
	while (p)
	{
		printf("%d ", p->data);
		p = p->next;
	}
	printf("\n");
}

void Clear(Stack *s)
{
	StackNode *p = s->next;
	while (p)
	{
		StackNode *temp = p;
		p = p->next;
		free(temp);
	}
	s->next = NULL;
}

int main()
{
	ElemType e;
	Stack s;
	Init(&s);
	for(int i = 1; i <= 20; ++i)
		Push(&s, i);
	Print(&s);

	GetTop(&s, &e);
	printf("栈顶的元素为:%d\n", e);

	Pop(&s, &e);
	GetTop(&s, &e);
	printf("出栈一次，栈顶的元素为:%d\n", e);

	Clear(&s);
	printf("清空该栈，此时");

	if(IsEmpty(&s))
		printf("栈为空\n");
	else
		printf("栈不为空\n");

	return 0;
}