数据结构—链栈

#include "StdAfx.h"
#include<stdio.h>
#include<stdlib.h>
#include<string.h>



//定义结点，栈顶，链栈类型

typedef int DataType;
struct Node
{
	DataType data;
	struct Node* next;
};
typedef struct Node *PNode;
typedef struct Node *top;
typedef struct Node *LinkStack;



//创建空栈
LinkStack SetNullStack()
{
	LinkStack top=(LinkStack)malloc(sizeof(struct Node));//申请栈顶空间，top指向
	if(top!=NULL)
		top->next =NULL;
	else
		printf("alloc failure");
	return top;//返回栈顶指针
}



//判断栈空

int IsNullStack(LinkStack top)
{
	return(top->next == NULL);
}



//进栈(头插,所以顺序相反，但对栈而言进出不影响，仍旧后进先出)

void Push(LinkStack top,DataType x)//x进栈
{
	PNode p=(PNode)malloc(sizeof(struct Node));//结点p，用于存放新进栈数据
	if(p!=NULL)
	{
		p->data =x;
		p->next =top->next ;//使p指针域为NULL
		top->next =p;
	}
	else
		printf("alloc failure!\n");
}



//出栈

void Pop(LinkStack top)
{
	PNode p;
	if(IsNullStack(top))
		printf("empty!\n");
	else
	{
		p=top->next ;//孤立p然后删除
		top->next =p->next ;
		free(p);
	}
}



//取栈顶元素

int top_seq(LinkStack top)
{
	if(IsNullStack(top))
		printf("empty!\n");
	else
		return top->next ->data ;
}



//打印链栈
void printLinkStack(LinkStack top)
{
	PNode p;
	if (top == NULL)
		printf("\n The Linklist is NULL !\n");
	p = top->next;
	while (p != NULL)
	{
		printf("%d", p->data);
		p = p->next;
	}

	printf("\n");
}



//主函数

int main()
{
	LinkStack stack1=SetNullStack();//创空栈

	Push(stack1,5);//进栈
	Push(stack1,8);
	Push(stack1,9);
	printLinkStack(stack1);

	Pop(stack1);//栈顶元素出栈
	printLinkStack(stack1);

	printf("the top of the stack is %d\n",top_seq(stack1));//返回栈顶元素
	printLinkStack(stack1);

	system("pause");
}