What happened when a destructor called in the constructor?

Question

I wrote this code as follows:

#include <iostream>



using namespace std;



class T

{

    public:

    T()

    {

        cout << "bb\n";

        this -> ~T();

        cout << "zz" << endl;

    }

    ~T()

    {

        cout << "hello\n";

    };

};







int main()

{

    T a;

    return 0;

}

Edited

Sorry, it should be

T a;

instead of

T a()

,and now I get the output:

bb

hello

zz

hello

But I'm confused about the result.Why this program can run successfully?

Edited

I don't think my question is duplicate. In my code, the constructor calls the destructor before the function is finished. However, it called twice destructor explicitly in that question.

Answer 1

This is undefined behaviour: you're calling the destructor on an object which has not yet been fully constructed.