Question

In the header, I’m defining bool isActive. In classes derived from this one, I would like to make isActive false by default. I tried doing this by adding

AbstractClass::isActive = false; 

to the cpp file, but that causes the error “Expected constructor, destructor, or type conversion before ‘=’ token.”

Answer 1

Initialize it in the class’ constructor:

class AbstractClass {
   bool isActive;

   AbstractClass() : isActive(false) {
   }

   // ...
};

That the class contains abstract methods doesn’t stop it from having a constructor that is used to initialize its member variables.