链式栈（C语言郝斌)

#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
typedef struct Node{
	int data;
	struct Node * pNext;
}NODE, * PNODE;

typedef struct Stack{
	PNODE pTop;
	PNODE pBottom;
}STACK, * PSTACK; //PSTACK等价于struct STACK * 

void init(PSTACK);
void push(PSTACK,int); 
void traverse(PSTACK);
bool pop(PSTACK,int *);
void clear(PSTACK);
int main(void){
	STACK S;//STACK 等价于struct Stack
	int val;
	init(&S); 
	push(&S,1);
	push(&S,2);
	push(&S,3);
	traverse(&S);
	clear(&S);
	traverse(&S);
//	if(pop(&S,&val)){
//		printf("出栈成功:%d\n",val);
//	}else printf("出栈失败\n");
//	traverse(&S);
	return 0;
} 
void init(PSTACK pS){
	pS->pTop=(PNODE)malloc(sizeof(NODE));
	if(NULL==pS->pTop){
		printf("动态内存分配失败!\n");
		exit(-1);
	}else{
		pS->pBottom=pS->pTop;
		pS->pTop->pNext=NULL;//pS->pBottom->pNext=NULL;
	}
}
void push(PSTACK pS,int val){
	PNODE pNew=(PNODE)malloc(sizeof(NODE));
	if(NULL==pNew){
		printf("动态内存分配失败!\n");
		return;
	}
	pNew->data=val;
	pNew->pNext=pS->pTop;
	
	pS->pTop=pNew;	
}
void traverse(PSTACK pS){
	PNODE p=pS->pTop;
	while(p!=pS->pBottom){
		printf("%d ",p->data);
		p=p->pNext;
	}
	printf("\n");
}
bool empty(PSTACK pS){
	if(pS->pTop==pS->pBottom){
		return true;
	}
	return false;
}
//把pS所指向的栈出栈一次 
bool pop(PSTACK pS,int * pVal){
	if(empty(pS)){
		return false;
	}
	PNODE p=pS->pTop;
	*pVal=p->data;
	pS->pTop=pS->pTop->pNext;
	free(p);
	p=NULL;
	return true;
}
void clear(PSTACK pS){
	//视频上的 
	if(empty(pS)){
		return;
	}
	PNODE p=pS->pTop;
	PNODE q=NULL;
	while(p!=pS->pBottom){
		q=p->pNext;
		free(p);
		p=q;
	}
	pS->pTop=pS->pBottom;
	/*
	// 
	PNODE p=NULL;
	while(pS->pTop!=pS->pBottom){
		p=pS->pTop;
		pS->pTop=pS->pTop->pNext;
		free(p);
		p=NULL;
	}*/
}