Re: please help with friend function in nested class template
LiDongning wrote:
I want to declare a function template as a friend in a nested class
template. The code is as follows.
template <class T>
class a1
{
public:
class a2
{
T att;
template <class T> friend const typename a1<T>::a2 operator +
.. ^^^^^
BTW, top-level const is ignored.
(const typename a1<T>::a2&, const typename a1<T>::a2&);
In order for a function to be declared a friend, it has to be declared
first. A function needs to be declared outside (before) the class a1
template. And since you're trying to get it to take 'a1's nested class
as its argument, and there is no forward-declaration of members, you're SOL.
};
};
template <class T>
const typename a1<T>::a2 operator + (const typename a1<T>::a2&, const
typename a1<T>::a2&)
{
return a1<T>::a2 xx;
Huh? Consider posting real code with which you have the problem.
}
int main()
{
a1<int> x;
a1<int>::a2 y;
y + y; //error! c2783
system("PAUSE");
return 0;
}
Complied in VC2008. Got error C2783. Tried couple of hours, just could
not make it work. Could somebody please help? Thanks very much!
V
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