【栈】链式栈

LinkedStack.h

#ifndef LINKEDSTACK_H
#define LINKEDSTACK_H

#include<iostream>
//Stack node
template<typename T>
struct stack_node{
	typedef stack_node<T>* pointer;
	T data;
	pointer next;
	stack_node() :next(NULL){}
	stack_node(const T value) :data(value), next(NULL){}
};
// LinkedStack
template<typename T>
class LinkedStack{
public:
	typedef T value_type;
	typedef T* pointer;
	typedef value_type& reference;
	typedef stack_node<T>* link_type;
	LinkedStack();//constructor
	~LinkedStack();//destructor
	void push(const T value);//push
	void pop();//pop
	reference get_top();//top
	bool empty();//whether LinkedStack is empty or not
	int size();//get length
private:
	void clear();//clear LinkedStack
private:
	link_type top;
};
//constructor
template<typename T>
LinkedStack<T>::LinkedStack():top(NULL){}
//destructor
template<typename T>
LinkedStack<T>::~LinkedStack(){
	clear();
}
//push
template<typename T>
void LinkedStack<T>::push(const T value){
	link_type p = new stack_node<T>(value);
	p->next = top;
	top = p;
}
//pop
template<typename T>
void LinkedStack<T>::pop(){
	if (empty()){
		std::cout << "there is no element in stack" << std::endl;
		exit(1);
	}
	link_type p = top;
	top = top->next;
	delete p;
}
//top
template<typename T>
typename LinkedStack<T>::reference LinkedStack<T>::get_top(){
	if (empty()){
		std::cout << "there is no element in stack" << std::endl;
		exit(1);
	}
	return top->data;
}
//whether stack is empty or not
template<typename T>
bool LinkedStack<T>::empty(){
	return top == NULL ? true : false;
}
//get length
template<typename T>
int LinkedStack<T>::size(){
	int count = 0;
	link_type p = top;
	while (p!=NULL){
		p = p->next;
		count++;
	}
	return count;
}
//clear LinkedStack
template<typename T>
void LinkedStack<T>::clear(){
	link_type p;
	while (top != NULL){
		p = top;
		top = top->next;
		delete p;
	}
}

#endif

main.cpp

#include"LinkedStack.h"
using namespace std;

int main(){
	LinkedStack<int> int_stack;
	cout << int_stack.size() << endl; //0
	cout << boolalpha << int_stack.empty() << endl;//true

	int_stack.push(1);
	cout << int_stack.size() << endl; //1
	cout << int_stack.get_top() << endl;//1
	int_stack.pop();

	for (int i = 0; i < 20; i++){
		int_stack.push(i);
	}

	cout << int_stack.size() << endl; //20
	cout << int_stack.get_top() << endl;//19
	cout << boolalpha << int_stack.empty() << endl;//false

	int_stack.push(21);
	cout << int_stack.get_top() << endl;//21
	int_stack.pop();

	cout << int_stack.get_top() << endl;//19
	int_stack.pop();

	int_stack.push(22);
	cout << int_stack.size() << endl; //20
	cout << int_stack.get_top() << endl;//22

	int_stack.pop();
	cout << int_stack.get_top() << endl;//18

	return 0;
}