CPlusPlusThings/basic_content/friend/friend_class.cpp

#include <iostream>

using namespace std;

class A {
public:
  A(int _a) : a(_a){};
  friend class B;

private:
  int a;
};

class B {
public:
  int getb(A ca) { return ca.a; };
};

int main() {
  A a(3);
  B b;
  cout << b.getb(a) << endl;
  return 0;
}