C + + member variable release problem

The phenomenon and background of the problem

I'm a beginner
Just look at the b One of the stations c++ course
The following figure is what he said

But I tried it myself, and the result was different from what he said ..

What's the reason , Is that tutorial wrong

Problem related code , Do not paste screenshots

Operation results and error reporting contents

My solution ideas and tried methods

What I want to achieve

#include<iostream>using namespace std;int* fun() { int a = 10; return &a;}int main(){ int* p = fun(); cout << *p << endl; cout << *p << endl; cout << *p << endl;}