C++ USES template classes to implement the chain stack

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1. Implementation procedures:

1.Stack.h

#ifndef Stack_h
#define Stack_h
 
template <class T>
class Stack {
public:
  Stack(){}; //  The constructor 
  void Push(const T x); //  New elements are added 
  bool Pop(); //  Top element out of the stack 
  virtual bool getTop(T &x) const = 0; //  Read top of stack elements by x return 
  virtual bool isEmpty() const = 0; //  Determines whether the stack is empty 
  // virtual bool isFull() const = 0; //  Determine if stack is full or not , Because there is no dissatisfaction with the chain stack 
  virtual int getSize() const = 0; //  Count the number of elements in the stack 
};
 
 
#endif /* Stack_h */

2.LinkedStack.h

#ifndef LinkedStack_h
#define LinkedStack_h
#include <iostream>
#include "Stack.h"
using namespace std;
 
template <class T>
struct LinkNode {
  T data;
  LinkNode<T> *link;
};
 
// Predeclaration of a class 
template <class T>
class LinkedStack;
 
// Declaration of a friend function 
template <class T>
ostream& operator<<(ostream& out, LinkedStack<T>& s);
template <class T>
class LinkedStack: public Stack<T> {
public:
  LinkedStack(); //  The constructor 
  ~LinkedStack();//  The destructor 
  void Push(const T x); //  Into the stack 
  bool Pop(); //  Out of the stack 
  bool getTop(T &x) const; //  Read top of stack elements 
  bool isEmpty()const; //  Determines whether the stack is empty 
  int getSize()const; //  Find the number of elements on the stack 
  void makeEmpty(); //  Empty the contents of the stack 
  friend ostream& operator << <T>(ostream& out, LinkedStack<T>& s); //  Overloaded output function 
private:
  LinkNode<T> *top; //  Stack top pointer, or chain head pointer 
};
template <class T>
LinkedStack<T>::LinkedStack() {
  //  Constructor, empty stack 
  top = new LinkNode<T>(); //  Incoming header pointer: does not hold data 
  top->link = NULL;
}
template <class T>
LinkedStack<T>::~LinkedStack() {
  //  The destructor , Free up memory space 
  makeEmpty();
}
template <class T>
void LinkedStack<T>::Push(const T x) {
  //  Push: To push the element value x Insert to the top of the chain stack, the chain head 
  LinkNode<T> *newNode = new LinkNode<T>(); //  Create contains x The new node 
  if(newNode == NULL) {
    cerr << " Memory space allocation failed! " << endl;
    exit(1);
  }
  newNode->data = x;
  newNode->link = top->link; //  Below the pointer to the head 1 Node: the stack in the first 1 A node that holds valid data 
  top->link = newNode; //  Move the head pointer forward 
}
template <class T>
bool LinkedStack<T>::Pop() {
  //  Out of stack: Removes the top of the stack 
  if(isEmpty())
    return false; //  Stack empty, not out of stack 
  LinkNode<T> *p = top->link; //  Top of the stack element 
  top->link = p->link; //  The stack top pointer falls back to the new stack top position 
  delete p;
  p = NULL;
  return true;
}
 
template <class T>
bool LinkedStack<T>::getTop(T &x) const {
  //  Read top of stack elements 
  if(isEmpty())
    return false;
  x = top->link->data; //  The stack is not empty. Returns the value of the top element. Here, top Is the header pointer, so the top element of the stack is: top->link
  return true;
}
 
template <class T>
bool LinkedStack<T>::isEmpty()const {
  //  Determines whether the stack is empty 
  if(top->link == NULL) //  The stack is empty 
    return true;
  return false;
}
 
template <class T>
int LinkedStack<T>::getSize()const {
  //  Find the number of elements on the stack 
  int len = 0;
  
  LinkNode<T> *current = top->link;
  while(current != NULL) {
    len++;
    current = current->link;
  }
  return len;
}
 
template <class T>
void LinkedStack<T>::makeEmpty() {
  //  Empty the contents of the stack 
  LinkNode<T> *current = top->link;
  while(current != NULL) {
    top->link = current->link; //  Save the node under the chain stack ready to be deleted 1 Three nodes to prevent loss 
    delete current; //  The release of 
    current = NULL; //  First points to an empty 
    current = top->link; //  And then point to the first node of the rest of the list 
  }
}
 
template <class T>
ostream& operator<<(ostream& out, LinkedStack<T>& s) {
  //  Overloaded output function 
  LinkNode<T> *current = s.top->link;
  while(current != NULL) {
    out << current->data << " ";
    current = current->link;
  }
  return out;
}
#endif /* LinkedStack_h */

3.main.cpp

#include "LinkedStack.h"
using namespace std;
 
int main(int argc, const char * argv[]) {
  int n, x, choice, len; // val The stored values, choose Store the user's choice 
  bool finished = false;
  LinkedStack<int> L; //  object 
  
  while(!finished) {
    cout << "1: Build the stack: " << endl;
    cout << "2: Into the stack " << endl;
    cout << "3: The stack: " << endl;
    cout << "4: Read top of stack elements: " << endl;
    cout << "5: Is the stack empty: " << endl;
    cout << "6: Number of elements in the stack: " << endl;
    cout << "7: Empty the contents of the stack: " << endl;
    cout << "8: Output the value of the element in the stack: " << endl;
    cout << "9: exit " << endl;
    cout << " Please enter your choice [1-9] : " << endl;
    cin >> choice;
    switch(choice) {
      case 1:
        cout << " Please enter the number of Numbers to be pushed :";
        cin >> n;
        cout << " Please enter the number to be pushed ( Space off ) : " << endl;
        for(int i=0; i < n; i++) {
          cin >> x;
          L.Push(x);
        }
        break;
      case 2:
        cout << " Please enter the number to be pushed :";
        cin >> x;
        L.Push(x);
        break;
      case 3:
        if(L.Pop())
          cout << " The stack is successful !" << endl;
        else
          cout << " The stack is empty !" << endl;
        break;
      case 4:
        if(L.getTop(x))
          cout << " The value of the top element of the stack is: " << x << endl;
        else
          cout << " The stack is empty !" << endl;
        break;
      case 5:
        if(L.isEmpty())
          cout << " The stack is empty! " << endl;
        else
          cout << " The stack is not empty !" << endl;
        break;
      case 6:
        len = L.getSize();
        cout << " The number of elements in the stack is: " << len << endl;
        break;
      case 7:
        L.makeEmpty(); //  Empty stack 
        break;
      case 8:
        if(L.isEmpty())
          cout << " The stack is empty! " << endl;
        else
          cout << L << endl;
        break;
      case 9:
        finished = true;
        break;
      default:
        cout << " Input error, please retype !" << endl;
    } // switch
  } // while
  return 0;
}