智能指針 get函數的問題

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

class A{
public:
    A(){
        cout << "A" << endl;
        q = new int(2);
    }
    ~A(){
        cout << "~A" << endl;
        delete q;
    }
    void p()
    {
        cout << *q << endl;
        
    }
    int *q;
};
 
int main()
{
    A *a;//聲明一個普通指針
    {
        //創建一個智能指針
        shared_ptr<A> p(new A());
        //返回給普通指針
        a = p.get();
        //打印值為2
        a->p(); 
        //出作用域，智能指針釋放，調用A析構函數
    }
    //打印值為0
    a->p();   
}