- Solution

#include <iostream>
class A{};
class B{};
class MyClass{
  public:
    MyClass(){}
    explicit MyClass(A){}                // since C++98
    explicit operator B(){return B();}   // new with C++11
};
void needMyClass(MyClass){};
void needB(B){};
struct MyBool{
  explicit operator bool(){return true;}
};
int main(){
  // A -> MyClass
  A a;
  // explicit invocation
  MyClass myClass1(a);
  // implicit conversion from A to MyClass
  MyClass myClass2=a;
  needMyClass(a);
  // MyClass -> B
  MyClass myCl;
  // explicit invocation
  B b1(myCl);
  // implicit conversion from MyClass to B
  B b2= myCl;
  needB(myCl);
  // MyBool -> bool conversion
  MyBool myBool;
  if (myBool){};
  int myNumber = (myBool)? 1998: 2011;
  // implict conversion
  int myNewNumber = myBool + myNumber;
  auto myTen = (20*myBool -10*myBool)/myBool;
  std::cout << myTen << std::endl;
}