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

#define INITIAL_STACK_SIZE 100
#define INCREASE_STACK_SIZE 10   // 大于一个元素的内存大小

typedef int ElemType;

typedef struct Stack
{
	ElemType *top;
	ElemType *base;
	int stacksize;   // 记录栈的大小
}Stack,*Pstack;

void InitStack(Pstack L);
void Push(Pstack L,ElemType i);
ElemType Pop(Pstack L);
void DestroyStack(Pstack L);
bool StackEmpty(Pstack L);
int StackLength(Pstack L);
ElemType GetTop(Pstack L);
void StackTraverse(Pstack L);

void main ()
{
	int size;

	Stack stack;
	Pstack L = &stack;
	InitStack(L);

	printf("请输入栈大小: ");
	scanf("%d",&size);

	for (int i = 1; i <= size; i++)
	{
		Push(L,i);
	}

	StackTraverse(L);

	if (StackEmpty)
	{
		printf("栈顶元素为：%d\n",GetTop(L));
		Pop(L);
		printf("弹栈 弹出栈顶元素：\n");
		StackTraverse(L);

		printf("栈内的元素个数为：%d\n",StackLength(L));
	}

	DestroyStack(L);

	L = NULL;
}


void InitStack(Pstack L)
{
	L->base = (ElemType *)malloc(INITIAL_STACK_SIZE * sizeof(ElemType));

	if (! L->base)
		exit(-1);
	L->top = L->base;
	L->stacksize = INITIAL_STACK_SIZE;
}

void Push(Pstack L,ElemType i)
{
	if (L->top - L->base >= L->stacksize){
		L->base =  (ElemType *)realloc(L->base,(INITIAL_STACK_SIZE+INCREASE_STACK_SIZE)* sizeof(ElemType));
		L->top = L->base + L->stacksize;
		L->stacksize += INCREASE_STACK_SIZE;
	}

	*(L->top++) = i;
}

ElemType Pop(Pstack L)
{
	if (L->top != L->base) // 栈不为空
	{
		i = * -- L->top;
	}

	return i;
}

void DestroyStack(Pstack L)
{
	for (ElemType * p = L->base; p < L->top; p++)
	{
		*p = 0;
	}
	L->top = L->base = NULL;
}

bool StackEmpty(Pstack L)
{
	if (L->base != L->top)
		return false;
	else
		return true;
}

int StackLength(Pstack L)
{
	int num = 0;

	for (ElemType * p = L->base; p < L->top; p++)
	{
		num++;
	}

	return num;
}

ElemType GetTop(Pstack L)
{
	ElemType e = * (L->top-1);

	return e;
}

void StackTraverse(Pstack L)
{
	ElemType * p = L->base;

	while (p != L->top)
	{
		printf("%d\t",*p++);
	}

	printf("\n");
}