VC-Compiler (2005) not ANSI-conform (using templates)?

[Physicus]

Hi,

I've found a strange behaviour of the C++ compiler of VS 2005. Because I'm not sure whether this is a bug (or a non-ANSI-comformity) or whether I've done a mistake, I post it here. The example is directly taken from Stroustrup's C++ bible.

Imagine two template classes (Vektor<> and Matr<>) for which you want to write an operator*(). Typically this operator-function is designed as being NOT a member of these classes, but a friend. The code is:

In the header file:
=============

template<class T> class Matr;

template<class T> class Vektor 
{
	T v[4];
public:
	friend Vektor operator*<> (const Matr<T>&, const Vektor&);
};

template<class T> class Matr
{
	Vektor<T> v[4];
public:
	friend Vektor<T> operator*<> (const Matr&, const Vektor<T>&);
};

template<class T> Vektor<T> operator*(const Matr<T>& m, const Vektor<T>& v)
{
	Vektor<T> vec = v;   // or do anything else...
	return v;
}

In the cpp file:
==========

	Vektor<int> vec;
	Matr<int> mat;

	Vektor<int> res = mat * vec;

During compilation VC gives the errors:
syntax error: missing ';' before '<'
and it points to the lines with the friend declarations.

When I remove the '<>' behind the operator* in the friend lines, than it compiles but the linker doesn't find the function (which is correct).
Normally, following the ANSI-syntax, the '<>' should be there. It seems that this is a bug of the VC++ compiler (VS 2005 with SP1).

Is there something wrong? Has anybody an idea/solution?

Thanks and bye,
Physicus.

[Physicus]

Hi gurus,

I found the (simple) solution:

One has to foreward declare the operator-Funktion, before it can be used as a friend in the class declarations. The foreward declaration looks like:

template<class T> Vektor<T> operator*(const Matr<T>&, const Vektor<T>&);

Then it works!

Bye,
Physicus.