栈的实现相较于链表还是很简单的，如果有些地方不太理解，可以去看看链表部分。

全部代码：

#define STDateType int

typedef struct Stack
{
	STDateType* a;
	int top;
	int capacity;
}ST;

void STInit(ST* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->top = 0;
	ps->capacity = 0;
}

void STDestroy(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->top = ps->capacity = 0;
}

void STPush(ST* ps, STDateType x)
{
	assert(ps);
	if (ps->top == ps->capacity)
	{
		int newcapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDateType* tmp = (STDateType*)realloc(ps->a, newcapacity * sizeof(STDateType));
		if (tmp == NULL)
		{
			perror("realloc:");
			return;
		}
		ps->a = tmp;
		ps->capacity = newcapacity;
	}

	ps->a[ps->top] = x;
	ps->top++;

}

void STPop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));
	ps->top--;
}

bool STEmpty(ST* ps)
{
	assert(ps);
	return ps->top == 0;
}

int STSize(ST* ps)
{
	assert(ps);
	return ps->top;
}

STDateType STTop(ST* ps)
{
	assert(ps);
	assert(!STEmpty(ps));
	return ps->a[ps->top - 1];
}