使用C++代码实现栈

```cpp
#include <iostream>
#include <vector>
 
template <typename T>
class Stack {
private:
    std::vector<T> elements;
 
public:
    void push(T element) {
        elements.push_back(element);
    }
 
    void pop() {
        if (!elements.empty()) {
            elements.pop_back();
        } else {
            std::cout << "Stack is empty. Cannot pop." << std::endl;
        }
    }
 
    T top() {
        if (!elements.empty()) {
            return elements.back();
        } else {
            std::cout << "Stack is empty." << std::endl;
            return T();
        }
    }
 
    bool empty() {
        return elements.empty();
    }
 
    int size() {
        return elements.size();
    }
};
 
int main() {
    Stack<int> myStack;
 
    myStack.push(5);
    myStack.push(10);
    myStack.push(15);
 
    std::cout << "Top element: " << myStack.top() << std::endl;
 
    myStack.pop();
    std::cout << "Top element after pop: " << myStack.top() << std::endl;
 
    std::cout << "Stack size: " << myStack.size() << std::endl;
 
    while (!myStack.empty()) {
        myStack.pop();
    }
 
    return 0;
}
```