棧（鏈式）

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

#define OK 0
#define ERROR -1
#define ElemType int

//定義棧的結點的結構
typedef struct Node
{
	ElemType data;
	Node *next;
}Node;

//定義棧的結構
typedef struct Stack
{
	Node *top;		//棧頂指針
	Node *bottom;	//棧底指針
}Stack;

//初始化一個棧
int initStack(Stack *pStack);
//壓棧
void pushStack(Stack *pStack, ElemType e);
//出棧
int popStack(Stack *pStack, ElemType *e);
//清空棧
void clearStack(Stack *pStack);
//遍歷輸出整個棧
void traverse(Stack *pStack);

int main()
{
	Stack stack;
	initStack(&stack);
	int e;
	pushStack(&stack, 1);
	pushStack(&stack, 2);
	pushStack(&stack, 3);
	pushStack(&stack, 4);
	pushStack(&stack, 5);
	
	traverse(&stack);
	
	popStack(&stack, &e);
	popStack(&stack, &e);
	printf("pop:%d\n", e);
	clearStack(&stack);
	popStack(&stack, &e);
	traverse(&stack);

	system("pause");
	return 0;
}

int initStack(Stack *pStack)
{
	//首先創建一個結點，此結點爲棧底結點的下一個結點，爲了方便操作
	Node *node = (Node *)malloc(sizeof(Node));
	if (!node)
	{
		printf("內存分配失敗，程序將退出\n");
		exit(EXIT_FAILURE);
	}
	//此結點的下一個結點爲NULL
	node->next = NULL;
	//棧頂和棧底指針都指向此結點
	pStack->top = pStack->bottom = node;

	return OK;
}

void pushStack(Stack *pStack, ElemType e)
{
	Node *newNode = (Node *)malloc(sizeof(Node));
	if (!newNode)
	{
		printf("內存分配失敗，程序將退出\n");
		exit(EXIT_FAILURE);
	}
	newNode->data = e;
	//新結點的下一個結點爲原棧頂結點
	newNode->next = pStack->top;
	//把棧頂修改爲新創建的結點
	pStack->top = newNode;
}

int popStack(Stack *pStack, ElemType *e)
{
	if (pStack->top == pStack->bottom)
	{
		printf("出棧失敗，棧爲空\n");
		return ERROR;
	}
	*e = pStack->top->data;
	//先取得棧頂元素
	Node *p = pStack->top;
	//把棧頂指針指向原棧頂元素的下一個元素
	pStack->top = p->next;
	//釋放原棧頂元素
	free(p);
	p = NULL;
	return OK;
}

void clearStack(Stack *pStack)
{
	Node *p = pStack->top;
	while (pStack->top != pStack->bottom)
	{
		p = p->next;
		free (pStack->top);
		pStack->top = p;
	}
}

void traverse(Stack *pStack)
{
	Node *p = pStack->top;
	while (p != pStack->bottom)
	{
		printf("%d ", p->data);
		p = p->next;
	}
	printf("\n");
}