#include <iostream>
 
using std::cout;
using std::endl;
 
class B;
 
class A {
  B* b_;
 
 public:
  A(B* b) : b_(b) { cout << "Конструктор А" << endl; }
  void func_1();
  void func_2() { cout << "Класс A func_2" << endl; }
};
 
class B {
  A a;
 
 public:
  B() : a(this) { cout << "Конструктор B" << endl; }
 
  void func_1() {
    cout << "Класс В func_1" << endl;
    a.func_1();
  }
 
  void func_2() {
    cout << "Класс В func_2" << endl;
    a.func_2();
  }
};
 
void A::func_1() {
  cout << "Класс А func_1" << endl;
  b_->func_2();
}
 
int main() {
  B b;
  b.func_1();
}
 

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