顺序栈c++

通过数组建立栈

#include <iostream>

using namespace std;

template<class T>
int ChangeSize1D(T *a, const int oldSize, const int newSize )
{
    if(newSize<0) throw "new length must be > 0";
    T *temp = new T[newSize];
    int num = min(oldSize, newSize);
    copy(a, a+num, temp);
    delete[] a;
    a = temp;
    return 0;
}

template<class T>
class MyStack
{
public:
    MyStack(int stackcapacity=10);
    ~MyStack();

    bool IsEmpty() const;
    T &Top() const;
    void Push(const T &item);
    void Pop();
private:
    T* Stack;
    int top;
    int capacity;
};

template<class T>
inline MyStack<T>::MyStack(int stackcapacity):capacity(stackcapacity)
{
    if(capacity<1) throw "capacity must be > 1";
    Stack = new T[capacity];
    top = -1;
}

template<class T>
MyStack<T>::~MyStack()
{
    delete[] Stack;
}

template<class T>
inline bool MyStack<T>::IsEmpty() const
{
    return top == -1;
}

template<class T>
inline T& MyStack<T>::Top() const
{
    if(IsEmpty()) throw "stack is empty";
    return Stack[top];
}

template<class T>
void MyStack<T>::Push(const T& item)
{
    if(top == capacity-1)
    {
        ChangeSize1D(Stack, capacity, 2*capacity);
    }
    Stack[++top] = item;
}

template<class T>
void MyStack<T>::Pop()
{
    if(IsEmpty()) throw "Stack cannot delete";
    Stack[top--].~T();
}

int main()
{
    MyStack<int> st;
    st.Push(99);
    st.Push(22);
    st.Push(13);

    cout << st.Top() << endl;
    st.Pop();
    cout << st.Top() << endl;
    st.Pop();
    cout << st.Top() << endl;
    st.Pop();
    cout << st.Top() << endl;
    st.Pop();
    cout << st.Top() << endl;
    cout << "Hello world!" << endl;
    return 0;
}