使用两个栈实现一个队列

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

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

~CQueue()
{}

void appendTail(const T& data)
{
stack1.push(data);
}

T deleteHead()
{
if( stack2.size() <= 0)
{
while(stack1.size() > 0)
{
T& data = stack1.top();
stack1.pop();
stack2.push(data);
}
}
if(stack2.size() == 0)
{
//throw new exception("query is empty");
}
T head = stack2.top();
stack2.pop();
return head;
}

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

};

int main()
{
CQueue<int> que;
que.appendTail(1);
que.appendTail(2);
que.appendTail(3);
que.appendTail(4);
que.appendTail(5);

cout<< que.deleteHead() << endl;
cout<< que.deleteHead() << endl;
cout<< que.deleteHead() << endl;
cout<< que.deleteHead() << endl;
cout<< que.deleteHead() << endl;

return 0;
}