Question

I have a tricky little problem I have run into. I believe the problem has to do with the way I am casting things.

So I have a base class called combatEntity. It has the following function

class combatEntity {
public:
    virtual void update();
};

I then have a class mob, which is derived from combatEntity, overrides the update function:

class mob : public combatEntity {
public:
    virtual void update();

}

I then have a class named monster, which is derived from mob and also overrides the update function.

class monster: public mob {
public:
    virtual void update();
}

I have a combatEntity pointer called i:

combatEntity* i;

Then I have:

//returns a mob* pointer (needs explicit cast)
monster* newMonster = getMob();
i = newMonster;

The getMob() function:

mob* getMob() {
   mob* newMob = new mob();
   //set some data in newMob
   return newMob;
}

When I call i->update(), it calls mob::update(), because newMonster is set to “new mob();”, since getMob() returns a new mob pointer. When I call i->update(), I need it to call monster::update(), but using breakpoints, I see it is calling mob::update() and not monster::update().

so I need to create a new monster object, but still have it’s base class data filled with the object returned from getMob(), but have the functions overridden properly. I have also tried dynamic_cast, static_cast and reinterpret_cast, and none seem to work. Or I need to cast my base class to a derived class, while properly overriding functions with the derived class.

Hopefully this makes sence. Any advice would be appreciated.

Answer 1

take a look to your hierarchy tree, make sure the classes are related how you think.

This code

#include <iostream>

struct combatEntity
{
    virtual void Update() { std::cout << "Combat Entity\n"; };
};

struct mob : combatEntity
{
    virtual void Update() { std::cout << "Mob\n"; };
};

struct monster : mob
{
    virtual void Update() { std::cout << "Monster\n"; };
};

int main(int argc, char **argv)
{
    combatEntity *ce = new monster;
    ce->Update();
    delete ce;

    return 0;
}

creates this output:

Monster

Source: http://ideone.com/k6LAB