出棧程序演示

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

typedef struct Node{
	int data;
	struct Node * pNext;
}NODE,*PNODE;

typedef struct Stack{
	PNODE pTop;        //棧頂元素
	PNODE pBottom;     //棧底部元素
}STACK,*PSTACK;

void init(PSTACK);
void push(PSTACK, int);
void traverse(PSTACK);

bool pop(PSTACK, int *p);
bool empty(PSTACK ps);   //判空

int main(void){

	STACK s;           //等價於struct Stack
	init(&s);            //初始化
	push(&s,1);            //壓棧 
	push(&s, 2);
	push(&s, 3);
	push(&s, 4);
	push(&s, 5);
	push(&s, 6);
	push(&s, 7);
	traverse(&s);      //遍歷輸出
	 
	int val;   //保存出棧的元素
	//出棧一個元素
	if (pop(&s, &val)) {
		printf("出棧成功，出棧的元素是%d\n", val);
	}else {
		printf("出棧失敗，出棧的元素是%d\n", val);
	}



	traverse(&s);      //遍歷輸出


	while (true){	}
	return 0;
}

//初始化造出一個空棧
void init(PSTACK ps) {

	ps->pTop = (PNODE)malloc(sizeof(NODE));
	if (NULL == ps->pTop) {
		printf("動態內存失敗");
		exit(-1);
	}else {
		 ps->pBottom= ps->pTop;
		ps->pTop->pNext = NULL;
	}
}

//壓棧
void push(PSTACK ps, int val) {
	//構造一個新的節點
	PNODE pNew=(PNODE)malloc(sizeof(NODE));
	pNew->data = val;
	pNew->pNext = ps->pTop;

	ps->pTop = pNew;
}


//遍歷
void traverse(PSTACK ps) {
	PNODE p = ps->pTop;

	while (p != ps->pBottom) {
		printf("%d   ",p->data);
		p = p->pNext;
	}

	printf("\n");
	return;
}

//把ps所指向的棧出棧一次，並把出棧的元素存入pVal形參所指向的變量中，如果出棧失敗，返回false，否則返回true
bool pop(PSTACK  ps, int *pVal) {

//如果爲空返回false
	if (empty(ps)) {
		return false;
	}else {
		PNODE tmp = ps->pTop; //構造一個臨時節點，存放ps指向頂部元素的地址（頂部元素是要出棧的）
		*pVal = tmp->data;    //出棧的元素
		ps->pTop=tmp->pNext;
		free(tmp);
		tmp = NULL;
		return true;
	}


}


bool empty(PSTACK ps) {
	if (ps->pTop == ps->pBottom) {
		return true;
	}
	else {
		return false;
	}
}