用兩個棧實現隊列

用兩個棧實現一個隊列，隊列聲明如下，實現它的兩個函數appendTail和deleteHead,分別完成在隊尾插入結點和在隊列頭部刪除結點的功能

template <typename T>
class CQueue
{
public:
CQueue();
~CQueue();

void appendTail(const T& nods);
T deleteHead();

private:
stack<T> stack1;
stack<T> stack2;
};

#include <iostream>
#include <stack>
#include <exception>
using namespace std;

template <typename T>
class CQueue
{
public:
CQueue(){};
~CQueue(){};

void appendTail(const T& nods);
T deleteHead();

private:
stack<T> stack1;
stack<T> stack2;
};

template <typename T>
void CQueue<T>::appendTail(const T& nods)
{
stack1.push(nods);
}

template <typename T>
T CQueue<T>::deleteHead()
{
if (stack2.size() == 0)
{
if (stack1.size() > 0)
{
while (stack1.size() > 0)
{
T& data = stack1.top();
stack1.pop();
stack2.push(data);
}
T& ret = stack2.top();
stack2.pop();
return ret;
}
else
throw new exception();
}
else
{
T ret = stack2.top();
stack2.pop();
return ret;
}
}

int main()
{
CQueue<int> myDeque;
myDeque.appendTail(1);
myDeque.appendTail(2);
myDeque.appendTail(3);
try{
cout << myDeque.deleteHead() << endl;
cout << myDeque.deleteHead() << endl;
} catch(exception ex) {
cout << "has exception" << endl;
}
return 0;
}