class interaction

How can I let two cl***** call a method from each other,
like in this example?

class A {
  B* myB;
  void doSomething() {
    myB->doSomething();
  }
};

class B {
  A* myA;
  void doSomething() {
    myA->doSomething();
  }
};

Thanks,
Dan