栈基本操作（C++实现）

#include <iostream>

using namespace std;

class ListStack;  //提前声明，友元函数需要

class ListNode
{
friend class ListStack;
public:
ListNode(int value):data(value), next(0) {}
private:
int data;
ListNode *next;
};

class ListStack
{
public:
ListStack():top(0) {}  //构造函数
ListStack(const ListStack&);  //拷贝构造函数
~ListStack();  //析构函数
ListStack& operator=(const ListStack&);  //赋值函数
bool isempty()const;  //判空
void push(int);  //入栈
bool pop();  //出栈
bool get_top(int&)const;  //取栈顶元素
protected:
private:
ListNode *top;
void copy(const ListStack&);  //拷贝功能函数
void clear();  //清空函数，实现析构
};

//拷贝功能函数
void ListStack::copy(const ListStack& other)
{
top = 0;
ListNode *tmp = other.top;
ListNode *prenode;
while (tmp)
{
ListNode *newnode = new ListNode(tmp->data);
if (top == 0)
{
top = newnode;
}
else
{
prenode->next = newnode;
}
prenode = newnode;
tmp = tmp->next;
}
}

//清空栈函数
void ListStack::clear()
{
while (top)
{
ListNode *delnode = top;
top = top->next;
delete delnode;
}
}

//拷贝构造函数
ListStack::ListStack(const ListStack& other)
{
copy(other);
}

//析构函数
ListStack::~ListStack()
{
clear();
}

//赋值函数
ListStack& ListStack::operator=(const ListStack& other)
{
if (this != &other)
{
clear();
copy(other);
}
return *this;
}

//判栈空函数
bool ListStack::isempty()const
{
return top == 0;
}

//入栈函数
void ListStack::push(int value)
{
ListNode *newnode = new ListNode(value);
newnode->next = top;
top = newnode;
}

//出栈函数
bool ListStack::pop()
{
if (isempty())
{
return false;
}
ListNode *delnode = top;
top = top->next;
delete delnode;
return true;
}

//取栈顶元素
bool ListStack::get_top(int &value)const
{
if (isempty())
{
return false;
}
value = top->data;
return true;
}

//主函数
int main()
{
ListStack s1;
for (int i=1; i<=6; ++i)
{
s1.push(i);
}
ListStack s2(s1);
ListStack s3;
s3 = s1;

int value;
while (s1.get_top(value))
{
s1.pop();
cout << value << " ";
}
cout << endl << "s1 已经清空" << endl;

while (s2.get_top(value))
{
s2.pop();
cout << value << " ";
}
cout << endl << "s2已经清空" << endl;

while (s3.get_top(value))
{
s3.pop();
cout << value << " ";
}
cout << endl << "s3已经清空" << endl;

return 0;
}