两个队列实现栈功能

key points:
template class and function, stack and queue.
Description:
In this assignment, you need to complete Class Stack's declaration and definition with Template. The different thing is that the Stack is implemented by two queues.  Following is the
example of Stack in integer:
class Stack {

  public:

    Stack(); // constructor.

    void push(const int& data); // push operation.

    int pop(); // return the value in the top and pop it out of the stack.

    int top(); // return the value in top.

    int size() const;  // return size of the stack.

    bool empty(); // check whether is empty.
  private:

    queue<int> q1; // two queues.

    queue<int> q2;

    int count; // the number of elements.

};
And you need to define a print function to print the content in the Stack from top to bottom. The format is: every element is followed by a blank space and an endl in the end.
Extra:
1. You are not allowed to use any STL except "queue". 
2. For more detail, see the codes in main.cpp.

#include <iostream>
#include <queue>
using namespace std;
template <typename T>
class Stack {  //  两个队列相互操作减少复杂度
private:
queue<T> p1;
queue<T> p2;
int count;
public:
Stack() {
count = 0;
}
void push(const T data) {
if (p2.size() > 0) {
p2.push(data);
} else {
p1.push(data);
}
++count;
}
T pop() {
T temp;
if (!empty()) {
if (p1.empty()) {
while (p2.size() > 1) {
p1.push(p2.front());
p2.pop();
}
temp = p2.front();
p2.pop();
} else {
while (p1.size() > 1) {
p2.push(p1.front());
p1.pop();
}
temp = p1.front();
p1.pop();
}
--count;
}
return temp;
}
T top() {
if (!p1.empty())
return p1.back();
return p2.back();
}
T size() const {
return count;
}
bool empty() {
return count == 0;
}
};

template <typename T>
void print(Stack <T> t) {
while (!t.empty()) {
cout << t.top() << " ";
t.pop();
}
cout << endl;
}

main函数：

#include "Stack.h"
#include<iostream>
#include<exception>

using namespace std;

class StackForbidden : public exception {
virtual const char *what() const throw() {
return "Please do not use Stack in stl..";
}
};

int main() {

#if defined(_GLIBCXX_STACK)
throw StackForbidden();
#endif

Stack<int> stack;
stack.push(88);
stack.push(44);
stack.push(99);

cout << "The size is: " << stack.size() << endl;
if (!stack.empty()) cout << stack.top() << endl;
print(stack);

stack.pop();
print(stack);

stack.push(777);
cout << "The size is: " << stack.size() << endl;
if (!stack.empty()) cout << stack.top() << endl;
print(stack);

stack.pop();
stack.pop();
cout << "The size is: " << stack.size() << endl;
print(stack);
stack.pop();
if (!stack.empty()) cout << stack.top() << endl;
else cout << "it is empty now." << endl;

Stack<double> stack1;
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i++) {
stack1.push(i + 0.01);
}
print(stack1);
while (m--) {
stack1.pop();
}
cout << "The size is: " << stack1.size() << endl;
if (!stack1.empty()) cout << stack1.top() << endl;
print(stack1);

}