C++ template friend function not linking

Question

I have the following code which compiles in VC6 :

Text.h:

template 
class CTextT
{
   public:

    friend  CTextT add(const CTextT&         


        

Answer 1

Of course it does give a linker error. The add() function you made a friend isn't a function template! It is a non-template function declared inside a class template. As a result, you won't be able to define this function as a template, either. You can directly define it at the friend declaration.

The alternative is to declare the function template prior to the class template. Of course, this requires a declaration of the class template, too. The following should work:

template  class CTextT;
template  CTextT add(CTextT const&, CTextT const&);
template 
class CTextT
{
    friend CTextT add<>(CTextT const&, CTextT const&);
    // ...
};

Now the template definition you have give should work.