// MyStack.cpp : 定义控制台应用程序的入口点。 //自己构造一个链式栈，具有push（入栈），pop（出栈），top（取得栈顶元素），size（返回栈大小），empty（判断是否为空）等功能 #include "stdafx.h" #include <iostream> using namespace std; //构造栈的节点 template <class T> struct NODE {  NODE<T>* next;  T data; }; template <class T> class MyStack { public:  MyStack()  {   phead = new NODE<T>;   if (phead == NULL)   {    cout << "Failed to malloc a new node. " << endl;   }   else   {    phead->data = NULL;    phead->next = NULL;   }  }  //入栈  void push(T e)  {   NODE<T>* p = new NODE<T>;   if (p == NULL)   {    cout << "Failed to malloc a new node. " << endl;   }   else   {    p->data = e;    p->next = phead->next;    phead->next = p;   }  }  //出栈  T pop()  {   T e;   NODE<T>* p = phead->next;   if(p != NULL)   {    phead->next = p->next;    e = p->data;    delete p;    return e;   }   else   {    cout << "There is no elements in the stack." << endl;    return NULL;   }  }  //取得栈顶元素  T top()  {   T e;   NODE<T>* p = phead->next;   if (p != NULL)   {    e = p->data;    return e;   }   else   {    cout << "There is no elements in the stack." << endl;    return NULL;   }  }  //取得栈中元素个数  int size()  {   int count(0);   NODE<T>* p = phead->next;   while (p != NULL)   {    p = p->next;    count++;   }   return count;  }  //判断stack是否为空  bool empty()  {   NODE<T>* p = phead;   if (p->next == NULL)   {    return true;   }   else   {    return false;   }  } private:  NODE<T>* phead; }; int _tmain(int argc, _TCHAR* argv[]) {  MyStack<int> sta;  sta.push(1);  sta.push(2);  sta.push(3);  cout << "The size of the stack now is " << sta.size() << endl;  sta.pop();  cout << "The top element is " << sta.top() << endl;  cout << "The size of the stack now is" << sta.size() << endl;  if (sta.empty())  {   cout << "This stack is empty." << endl;  }  else  {   cout << "This stack is not empty." << endl;  }  return 0; }