Re: void function returning value?

From: tom_usenet (tom_usenet_at_hotmail.com)
Date: 02/25/04 

Date: Wed, 25 Feb 2004 14:32:05 +0000

On Wed, 25 Feb 2004 12:11:17 +0100, "Jochen Zeischka"
<jochen.zeischka@rug.ac.be> wrote:

>I'm puzzled. When compiling this:
>
>template<class ValRes, class Val1, class Val2>
>Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1, const
>Veld<Val2>& v2) {
> // something
> return res;
>}
>
>the compiler says:
>
>error C2562: 'mult' : 'void' function returning a value
>c:\fe dev\lin lag 9\veld.h(64) : see declaration of 'mult'
>
>which is the following line within the 'Veld' class:
>
> template<class ValRes, class Val1, class Val2>
> friend Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1, const
>Veld<Val2>& v2);
>
>forward declaration of the friend function was done as follows:
>
>template<class Val> class Veld;
>
>template<class ValRes, class Val1, class Val2>
>Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1, const
>Veld<Val2>& v2);
>
>Why is the compiler talking about a 'void' function? To me it seems that a
>'Veld<ValRes>&' is returned...

To me too. This compiled fine for me on 3 compilers:

template<class Val>
class Veld;

template<class ValRes, class Val1, class Val2>
Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1, const
Veld<Val2>& v2);

template<class Val>
class Veld
{
 template<class ValRes, class Val1, class Val2>
 friend Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1,
const Veld<Val2>& v2);
 //private var to test friendship
 Val v;
};

template<class ValRes, class Val1, class Val2>
Veld<ValRes>& mult(Veld<ValRes>& res, const Veld<Val1>& v1, const
Veld<Val2>& v2)
{
  res.v = v1.v + v2.v;
  return res;
}

int main()
{
  Veld<double> v1;
  Veld<int> v2;
  Veld<short> v3;
  Veld<double> v = mult(v1, v2, v3);
}

What compiler are you using? Can you post a complete program
exhibiting the error?

Tom 

-- 
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