Example work of constructor

learn_work_of_constructor.cpp

#include <iostream>
 
struct A
{
    A() { std::cout << "A constructed successfully\n"; }
    ~A(){ std::cout << "A destroyed\n"; }
};
 
struct B
{
    A a1, a2, a3;
    B() { std::cout << "B constructed successfully\n"; }
    ~B(){ std::cout << "B destroyed\n"; }
};
 
struct C : A, B
{
    C() { std::cout << "C constructed successfully\n"; }
    ~C(){ std::cout << "C destroyed\n"; }
};
 
int main ()
{
    C c;
    
    return 0;
}

Output:
A constructed successfully
A constructed successfully
A constructed successfully
A constructed successfully
B constructed successfully
C constructed successfully
C destroyed
B destroyed
A destroyed
A destroyed
A destroyed
A destroyed