#include <iostream>
#include <deque>
template <typename T>
class Stack
{
private:
std::deque<T> elems; // elements
public:
void push(T const&); // push element
void pop(); // pop element
T top() const; // return top element
bool empty() const
{ // return whether the stack is empty
return elems.empty();
}
// assign stack of elements of type T2
template <typename T2>
Stack<T>& operator= (Stack<T2> const&);
};
template <typename T>
void Stack<T>::push(T const& elem)
{
elems.push_back(elem); // append copy of passed elem
}
template<typename T>
void Stack<T>::pop()
{
if (elems.empty())
{
throw std::out_of_range("Stack<>::pop(): empty stack");
}
elems.pop_back(); // remove last element
}
template <typename T>
T Stack<T>::top() const
{
if (elems.empty())
{
throw std::out_of_range("Stack<>::top(): empty stack");
}
return elems.back(); // return copy of last element
}
template <typename T>
template <typename T2>
Stack<T>& Stack<T>::operator= (Stack<T2> const& op2)
{
if ((void*)this == (void*)&op2)
{ // assignment to itself?
return *this;
}
Stack<T2> tmp(op2); // create a copy of the assigned stack
elems.clear(); // remove existing elements
while (!tmp.empty())
{ // copy all elements
elems.push_front(tmp.top());
tmp.pop();
}
return *this;
}
int main()
{
try {
Stack<int> intStack; // stack of ints
Stack<float> floatStack; // stack of floats
// manipulate int stack
intStack.push(42);
intStack.push(7);
// manipulate float stack
floatStack.push(7.7);
// assign stacks of different type
floatStack = intStack;
// print float stack
std::cout << floatStack.top() << std::endl;
floatStack.pop();
std::cout << floatStack.top() << std::endl;
floatStack.pop();
std::cout << floatStack.top() << std::endl;
floatStack.pop();
}
catch (std::exception const& ex)
{
std::cerr << "Exception: " << ex.what() << std::endl;
return EXIT_FAILURE; // exit program with ERROR status
}
return 0;
}
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