std::cout in debug is displayed in terminal only when the program terminates

So lets say I have a program like this : 

#include <iostream>
#include <typeinfo>

using namespace std;

class A {
public:
    A() { cout << "1"; }

    A(const A &obj) { cout << "2"; }
};

class B :   public A {
public:
    B() { cout << "3"; }

    B(const B &obj) { cout << "4"; }
};

class C : virtual public A {
public:
    C() { cout << "5"; }

    C(const C &obj) { cout << "6"; }

};

class D : B,C {
public:
    D() { cout << "7"; }

    D(const D &obj) { cout << "8"; }

};

int main() {

    D d2;
    D d(d2);
    return 0;
}

and I want to follow on the building process of each object (inheritance process practice) with cout, the problem is that the final phrase is displayed in 1 piece when the program terminates after return 0, instead of printing a number 1 by 1 in each step I take with "step into". is there any way to configure it instead of using fflush (stdout) in each cout command?

Thank you.