Linker chokes on virtual methods

I don't know if this is a Qt issue, or that I'm not chaining my virtual types correctly. I am getting the same thing on a number of virtual functions. Below is an example.

I have

Code:

---

class entity_ao {
   public:
 
  ...
 
     virtual void setToZero();
 
  ...
}
 
class scalar_ao : public entity_ao {
  ...   
}
 
class real_ao : public scalar_ao {
   public:
 
   ...
 
   void setToZero() { ... }
 
   ...
}

---

This compiles just fine, but the .NET 2003 linker says: LNK2001: unresolved external symbol public: virtual void __thiscall entity_ao::setToZero(void)

I have tried adding virtual void setToZero(); to class scalar_ao, but that changes nothing. I have also tried moving the defn forreal_ao::setToZero from the .h to a .cpp file -- again that changes nothing.

Ignore my post on this subject. I just figured out that the base class needs an instantiation of the virtual function. Doing that gets rid of the linker errors.

K.

You can also make the method pure virtual in the base class:

Code:

---

class entity_ao {
   public:
 
  ...
 
     virtual void setToZero() = 0;
 
  ...
}

---

The linker won't complain then.