// For exercise.
// This program illustrates a slightly surprised construction of the A-part of a D-object.
// A D object has a B-part and a C-part, in both of which we make use of our own default constructors. Both of these delegates to to A(int).
// But it turns out that A(int) is NOT used in the construction of a D-object. 
// Surprise, probably! Please - as an exercise - consider this issue.

#include <iostream>
#include <string>

using namespace std;

class A {
public:
  int a;
  A(): a(9){}
  A(int a): a(a){}
};

class B : public virtual A {
public:
  int b;
  B(): A(5), b(1){}                 // A(int) is ignored in the actual construction of the D-object in main.
};

class C : public virtual A {
public:
  int c;
  C(): A(7), c(2){}                 // A(int) is ignored in the actual construction of the D-object in main.
};

class D : public B, public C {
public:
  int d;
  D(): d(9){}                       // Use the default constructors of B and C
};


int f(D &x){
  cout << x.a << endl;     // 9     // We se that The default constructor in A have been used.
  cout << x.B::a << endl;  // 9
  cout << x.C::a << endl;  // 9
  cout << x.b << endl;     // 1 
  cout << x.c << endl;     // 2
  cout << x.d << endl;     // 9
}

int main(){
  D d;
  f(d);
}