C++中用两个标准容器stack,实现一个队列的方法详解

// StackToQueue.cpp : 定义控制台应用程序的入口点。
//用两个标准容器stack，实现一个队列
#include "stdafx.h"
#include <iostream>
#include <stack>
using namespace std;
template <class T>
class StackToQueue
{
public:
 StackToQueue()
 {
  stack1;
  stack2;
 }
 void push(T e)
 {
  while (!stack2.empty())
  {
   T temp;
   temp = stack2.top();
   stack2.pop();
   stack1.push(temp);
  }
  stack2.push(e);
  while (!stack1.empty())
  {
   T temp;
   temp = stack1.top();
   stack1.pop();
   stack2.push(temp);
  }
 }

 void pop()
 {
   stack2.pop();
 }

 T front()
 {
  if (!empty())
  {
   return stack2.top();
  }
  else
  {
   return NULL;
  }
 }
 bool empty()
 {
  return stack2.empty();
 }
 size_t size()
 {
  return stack2.size();
 }
private:
 stack<T> stack1, stack2;
};
int _tmain(int argc, _TCHAR* argv[])
{
 StackToQueue<int> queue;
 int i(0);
 cout << "Enter several integer number,and press ctrl+z to the end." << endl;
 while (cin >> i)
 {
  queue.push(i);
 }
 cout << "The front element is: " << queue.front() << endl;
 cout << "The size now is: " << queue.size() << endl;
 if (!queue.empty())
 {
  cout << "Pop one element now." << endl;
  queue.pop();
 }
 cout << "The front element is: " << queue.front() << endl;
 cout << "The size now is: " << queue.size() << endl;
 return 0;
}