error: out-of-line definition of 'test' does not match any declaration in 'B<dim>'

Question

I have a small problem that is killing me!! I don't know what seems to be wrong with the below code. I should be able to implement the function that is inherited from the super class, shouldn't I? but I get error: out-of-line definition of 'test' does not match any declaration in 'B<dim>'

template <int dim>
class A 
{
public:
  virtual double test() const ;
};

template <int dim>
class B : public A <dim>
{
};

template <int dim>
double B<dim>::test () const
{
  return 0;
}

I am on a Mac using clang (Apple LLVM version 5.1).

Answer 1

Try

template <int dim>
class B : public A <dim>
{
public:
     virtual double test () const;
};

// Function definition
template <int dim>
double B<dim>::test () const
{
  return 0;
}

You still need to define the function declared the class declaration.

Answer 2

The problem is that you are trying to define function test outside the class definition of class B. You have to declare it at first in the class

template <int dim>
class B : public A <dim>
{
   double test() const;
};