栈的子函数

#include<iostream>
#include<string>

typedef int ElemType;

struct SNode
{
	ElemType data;
	SNode* next;
};

void InitStack(SNode*& HS)
{
	HS = NULL;
}

void Push(SNode*& HS, const ElemType& item)
{
	SNode* newptr = new SNode;
	newptr->data = item;
	newptr->next = HS;
	HS = newptr;
}

ElemType Pop(SNode*& HS)
{
	if (HS == NULL)
	{
		std::cerr << "Linked stack is empty!" << std::endl;
		exit(1);
	}
	SNode* p = HS;
	HS = HS->next;
	ElemType temp = p->data;
	delete p;
	return temp;
}

ElemType Peek(SNode* HS)
{
	if (HS == NULL)
	{
		std::cerr << "Linked stack is empty!" << std::endl;
		exit(1);
	}
	return HS->data;
}

bool EmptyStack(SNode* HS)
{
	return HS == NULL;
}

void ClearStack(SNode*& HS)
{
	SNode *cp, *np;
	cp = HS;
	while (cp!=NULL)
	{
		np = cp->next;
		delete cp;
		cp = np;
	}
	HS = NULL;
}