Cannot understand friend functions in a template class
c++, friend, templates
Solution
As per [temp.friend], you must provide explicit template arguments to make a specialisation of a template function a friend:
template <class T>
class D
{
public :
friend void print<T>(D <T> obj);
};
Without it, the compiler will be looking for a function `print()`, not a function template `print()`.
Problem
This is code i have written to understand the concept. The code is fine and it runs. What i dont understand is that why is the marked line needed ? ``` template <class T> class D { public : template <class P> //<------------------Why is this needed ? -------------- friend void print(D <P> obj); }; template <class T> void print(D<T> obj) {std::cout<<sizeof(T);}; int main() { D <char>obj3; print(obj3); return 0; } ``` or in other words why does the following not run ? ``` template <class T> class D { public : friend void print(D <T> obj); }; ```